Download - Abortion
Williams Obstetrics
Chapter 9 Abortion
OBGY R1 Lee Eun Suk
Abortion
Spontaneous abortiono Pathology
o Etiology
o Fetal Factors
o Maternal Factors
o Paternal Factors
o Categories of Spontaneous Abortion
Induced abortiono History of abortion
o Indications
o Elective (Voluntary) Abortion
Presumption of ovulation after abortion
Abortion
Termination of pregnancy, either spontaneously or intentionally
Pregnancy termination prior to 20 weeks’ gestation or less than 500-g birthweight
Definition vary according to state laws for reporting abortions, fetal deaths, and neonatal deaths
Spontaneous abortion
Abortion occurring without medical or mechanical means to empty the uterus is referred to as spontaneous
Another widely used term is miscarriage
Pathology o Hemorrhage into the decidua basinalis, followed by necrosis of tissues adjacent to the bleeding
o If early, the ovum detaches, stimulating uterine contractions
that result in its ovulation
o Gestational sac is opened , fluid surrounding a small macerated
fetus or alternatively no fetus is visible → blighted ovum
Spontaneous abortion
Pathology
o In later abortion, the retained fetus may undergo maceration
The skull bones collapse, the abdomen distends with blood-
stained fluid, and the internal organs degenerate
The skin softens and peels off in utero or at the slightest tough
o When amnionic fluid is absorbed, the fetus may become compressed and desiccated → fetal compressus
o The fetus become so dry and compressed that it resembles parchment - a fetus papyraceous
Spontaneous abortion
Etiology
o More than 80 percent of abortions occur in the first 12 weeks of pregnancy
o At least half result from chromosomal anomalies
o After the first trimester, both the abortion rate & the incidence of chromosomal anomalies decrease
F9-1
Spontaneous abortion
Etiology
o The risk of spontaneous abortion increases with parity as well as with maternal and paternal age
o The frequency of abortion increases from 12 percent in women younger than 20 years to 26 percent in those older than 40 years
o If a woman conceives within 3 months following a term birth
→ incidence of abortion ↑
F9-2
Spontaneous abortion
Etiology
o The exact mechanism responsible for abortion are not apparent
o In the first 3 months of pregnancy
Death of the embryo or fetus nearly always precedes spontaneous expulsion of the ovum
Finding of the cause of early abortion involves ascertaining
the cause of fetal death
o In subsequent months
The fetus frequently does not die before expulsion
Other explanations for its expulsion should be sought
Spontaneous abortion - Fetal factors
Abnormal zygotic development
o Early spontaneous abortion commonly display a developmental abnormality of the zygote, embryo, early fetus, or placenta
o 1000 spontaneous abortions analyzed by Hertig and Sheldon
Half demonstrated degenerated or absent embryos, that is,
blighted ova
F9-3
Spontaneous abortion - Fetal factors
Aneuploid abortion
o Approximately 50 to 60 percent of embryos and early fetuses
that are spontaneously aborted contain chromosomal abnor-malities accounting for most of early pregnancy wastage
o Jacobs and Hassold (1980)
95 percent of chromosomal abnormalities
d/t maternal gametogenesis error
5 percent → d/t paternal error
T9-1
Spontaneous abortion - Fetal factors
Aneuploid abortion - Autosomal trisomy
o The most frequently identified chromosomal anomaly associated with first-trimester abortions
o Most trisomies result from isolated nondisjunction , balanced structural chromosomal rearrangements are present in one partner in 2 to 4 percent of couples with a history of recurrent abortions
o Autosomes 13, 16, 18, 21, and 22 – most commom
Spontaneous abortion - Fetal factors
Monosomy X
o The second frequent chromosomal abnormality
o Usually results in abortion
o Much less frequently in liveborn female infant (Turner syndrome)
Triploidy
o Associated with hydropic placental (molar) degeneration
o Incomplete (partial) hydatidiform moles may contain triploidy or trisomy for only chromosome 16
Spontaneous abortion - Fetal factors
Tetraploid abortuses
o Rarely are liveborn and most often are aborted early in gestation
Chromosomal structural abnormalities
o Identified only since the development of banding techniques, infrequently cause abortion
Spontaneous abortion - Fetal factors
Euploid abortion
o Abort later in gestational than aneuploid
o Three fourths of aneuploid abortions occurred before8 weeks
o Euploid abortions peak at about 13 weeks
o The incidence of euploid abortions increased dramatically after maternal age exceeded 35 years
Spontaneous abortion – Maternal factors
Infections
o Uncommon causes of abortion in human
Listeria monocytogenes
Clamydia trachomatis
Mycoplasma hominis
Ureaplasma urealyticum
Toxoplasma gondii
Spontaneous abortion – Maternal factors
Chronic debilitating diseases
o In early pregnancy, fetuses seldom abort secondary to chronic wasting disease such as tuberculosis or carcinomatosis
o Celiac sprue
Cause both male and female infertility and recurrent abortions
Spontaneous abortion – Maternal factors
Endocrine abnormalities
o Hypothyroidism
Iodine deficiency associated with excessive miscarriages
Thyroid autoantibodies → incidence of abortion↑
o Diabetes mellitus
The rates of spontaneous abortion & major congenital malformations
Poor glucose control → incidence of abortion↑
o Progesterone deficiency
Luteal phase defect
Insufficient progesterone secretion by the corpus luteum or placenta
Poor glucose control → incidence of abortion↑
Spontaneous abortion – Maternal factors
Nutritiono Dietary deficiency of any one nutrients → not important cause
Drug use and environmental factor o Tobacco
↑ Risk for euploid abortion
More than 14 cigarettes a day → the risk twofold greater ↑
o Alcohol
Spontaneous abortion & fetal anomalies → result from frequent alcohol use during the first 8 weeks of pregnancy
Drinking twice a week → abortion rates doubled ↑
Drinking daily → abortion rates tripled ↑
o Caffeine
At least 5 cups of coffee per day → slightly increased risk of abortion
Spontaneous abortion – Maternal factors
Drug use and environmental factor
o Radiation
In sufficient doses → abortifacient
o Contraceptives
When intrauterine devices fail to prevent pregnancy → abortion↑
o Environmental toxins
Anesthetic gases : exact fetal risk of chronic maternal exposure is unknown
Arsenic, lead, formaldehyde, benzene, ethylene oxide → abortifacient
Video display terminal & accompanying electromagnetic fields
short waves & ultrasound do not increase the risk of abortion
Spontaneous abortion – Maternal factors
Immunological factors – autoimmune factorso Recurrent pregnancy loss patients : 15%
o Antiphospholipid antibody : most significant
LCA (lupus anticoagulant), ACA (anticardiolipin Ab)
Reduce prostacyclin production
→ facilitating thromboxane dominant milieu → thrombosis
Prostacyclin : produced by vascular endothelial cell
→ potent vasodilator & inhibit platelet aggregation
Thromboxane A2 : produced by platelets
→ vasoconstrictor & platelet aggregator
Strong association with
Decidual vasculopathy , placental infarction, fetal growth restriction
Early-onset preeclampsia, recurrent abortion, fetal death
Spontaneous abortion – Maternal factors
Immunological factors – autoimmune factors
o Therapy of antiphopholipid antibody syndrome
: low dose aspirin, prednisone, heparin, intravenous Ig
→ affect both immune & coagulation system
→ counteract the adverse action of antibodies
Spontaneous abortion – Maternal factors
Immunological factors – alloimmune factors
o Allogeneity
Genetic dissimilarities between animals of the same species
Human fetus is allogenic transplant tolerated by mother
o Several test for diagnosis of alloimmune factors
Maternal & paternal HLA comparison
Maternal serum test for blocking antibodies
: blocking antibodies to paternal antigens
: ig G origin
Maternal serum test for antipaternal antibodies
: cytotoxic antibodies to paternal leukocyte
Spontaneous abortion – Maternal factors
Inherited thrombophiliao Many studies of aggregated thrombophilias
→ excessive recurrent abortions
Laparotomyo Surgery performed during early pregnancy
→ no evidence of tncreased abortion
o Peritonitis increases the likelihood of abortion
Physical trauma
o Major abdominal trauma → abortion↑
Spontaneous abortion – Maternal factors
Uterine defects – acquired uterine defectso Uterine leiomyoma : usually do not cause abortion
Placental implantation over or in contact with myoma
→ placental abruption, abortion, preterm labor ↑
→ location is more important than size
o Uterine synechiae (Asherman syndrome)
Partial or complete obliteration of the uterine cavity by adherence of uterine wall
Cause : destruction of large areas of endometrium by curettage
→ insufficient endometrium to support implantation & menstruation
→ recurrent abortion, amenorrhea, hypomenorrhea
Spontaneous abortion – Maternal factors
Uterine defects – acquired uterine defects
o Diagnosis of uterine synechiae
Hysterosalpingogram → characteristic multiple filling defects
Hysteroscopy → most accurate & direct diagnosis
o Treatment of uterine synechiae
Lysis of adhesions via hysteroscopy
Prevention of adherence : IUD
Promotion of endometrial proliferation
: Continuous high-dose estrogen (60-90 days)
Spontaneous abortion – Maternal factors
Uterine defects – developmental uterine defects Consequence of abnormal mullerian duct formation or fusion
Spontaneously
Induced by in utero exposure to DES (diethylstilbestrol)
Spontaneous abortion – Maternal factors
o Incompetent cervix Painless dilatation of cervix in the 2nd or early in the 3rd trimester
→ prolapse & ballooning of membranes into vagina
→ rupture of membrane & expulsion of immature fetus
Unless effectively treated, tends to repeat in each pregnancy
Diagnosis in nonpregnant women
Hysterography
Pull-through techniques of inflated Foley catheter balloons
Acceptance without resistance at the internal os of specifically sized cervical dilators
The use of transvaginal ultrasound in pregnant women
Cervical length - shortening
Funneling
Spontaneous abortion – Maternal factors
o Incompetent cervix – Etiology Previous trauma to the cervix
Dilatation & curettage
Conization
Cauterization
Abnormal cervical development Exposure to DES in utero
Spontaneous abortion – Maternal factors
o Incompetent cervix – Treatment The operation is performed to surgically
Reinforcement of weak cervix by some type of purse string suture
( Cerclage )
Prophylactic surgery : generally performed between 12 & 16weeks
Should be delayed until after 14 weeks’ gestation
→ Early abortion due to other factors will be completed
The more advanced the pregnancy, the more likely the risk that surgical intervention stimulate preterm labor or membrane rupture
Usually do not perform after about 23 weeks
Spontaneous abortion – Maternal factors
o Incompetent cervix – Preoperative evaluation Sonography
: Confirm living fetus & exclude major fetal anomalies
Cervical cytology
Cultures for gonorrhea, chlamydia, group B streptococci Obvious cervical infections → treatment is given
For at least a week before & after surgery → sexual intercourse should be restricted
Spontaneous abortion – Maternal factors
o Incompetent cervix – Cerclage procedures Types of operations commonly used
McDonald Modified Shirodkar
→ 85~90% success rate
Spontaneous abortion – Maternal factors
o Incompetent cervix – Transabdominal cerclage Requries laparotomy for
Placement of cerclage at uterine isthmus level
Cerclage removal, delivery, or both
Indications Anatomical defects of cervix
Failed transvaginal cerclage
Spontaneous abortion – Maternal factors
o Incompetent cervix – Complications High incidence when performed much after 20 weeks
Membranes ruptures
Chorioamnionitis
Intrauterine infection
Urgent removal of suture Operation fails
Signs of imminent abortion or delivery
Spontaneous abortion – Paternal factors
o Little is known in the genesis of spontaneous abortiono Chromosomal translocations in sperm can lead to abortion
Categories of spontaneous abortion
o Threatened abortiono Inevitable abortion o Complete or incomplete abortion o Missed abortion o Recurrent abortion
Threatened abortion
o Definition Any bloody vaginal discharge or bleeding during 1st half of pregnancy
Bleeding is frequently slight, but may persist for days or weeks
o Frequency Extremely common (one out of four or five pregnant women)
o Prognosis Approximately ½ will abort
Risk of preterm delivery, low birthweight, perinatal death↑
Risk of malformed infant does not appear to be increased
Categories of spontaneous abortion
o Symptoms Usually bleeding begins first
Cramping abdominal pain follows a few hours to several days later
Presence of bleeding & pain
→ Poor prognosis for pregnancy continuation
o Treatment Bed rest & acetaminophen-based analgesia
Progesterone (IM) or synthetic progestational agent (PO or IM)
Lack of evidence of effectiveness
Often results in no more than a missed abortion
D-negative women with threatened abortion
Probably should receive anti-D immunoglobulin
Threatened abortion
Categories of spontaneous abortion
Threatened abortion
o Treatment : slight bleeding persists for weeks Vaginal sonography
Serial serum quantitative hCG
Serum progesterone
→ can help ascertain if the fetus is alive & its location
o Vaginal sonography Gestational sac(+) & hCG < 1000mIU/ml
→ gestation is not likely to survive
→ If any doubt(+), check the serum hCG level at intervals of 48hrs
→ if not increase more than 65%, almost always hopeless
Serum progesterone value < 5 ng/ml
→ dead conceptus
Categories of spontaneous abortion
Threatened abortion
o Treatment : after death of conceptus Uterus should be emptied
→ examination of all passed tissue whether the abortion is complete
Ectopic pregnancy should be considered if gestational sac or
fetus are not identified
Categories of spontaneous abortion
Inevitable abortion
o Gross rupture of membrane,evidenced by leaking amnionic fluid, in the presence of cervical dilatation, but no tissue passed during 1st half of pregnancy
Placenta (in whole or in part) is retained in the uterus
→ Uterine contractions begin promptly or infection develops
The gush of fluid is accompanied by bleeding, pain, or fever, abortion should be considered inevitable
Categories of spontaneous abortion
o Complete abortion Following complete detachment & expulsion of the conceptus
The internal cervical os closes
o Incomplete abortion Expulsion of some but not all of the products of conception during 1st half of pregnancy
The internal cervical os remains open & allows passage of blood
The fetus & placenta may remain entirely in utero or may partially extrude through the dilated os
→ Remove retained tissue without delay
Complete or incomplete abortion
Categories of spontaneous abortion
o Retention of dead products of conception in utero for several weeks Many women have no symptoms except persistent amenorrhea Uterus remain stationary in size, but mammary changes usually
regress → uterus become smaller
Most terminates spontaneously
Serious coagulation defect occasionally develop after prolonged retention of fetus
Missed abortion
Categories of spontaneous abortion
o Definition : Three or more consecutive spontaneous abortionso Clinical investigation of recurrent miscarriage
Parental cytogenetic analysis
Lupus anticoagulant & anticardiolipin antibodies assays
o Postconceptional evaluation Serial monitoring of Я–hCG from missed mens period
Я–hCG>1500mIU/ml → USG
Maternal serum α-fetoprotein assessment (GA16-18wks)
Amniocentesis → fetal karyotype
o Prognosis Depends on potential underlying etiology & number of prior losses
Recurrent abortion
Categories of spontaneous abortion
INDUCED ABORTION
o The medical or surgical termination of pregnancy before the time of fetal viability
o Therapeutic abortion Termination of pregnancy before of fetal viability for the purpose
of saving the life of the mother
Induced abortion
Induced abortion
Indication
o Continuation of pregnancy may threaten the life of women or seriously impair her health Persistent heart disease after cardiac decompensation
Advanced hypertensive vascular disease
Invasive carcinoma of the cervix
o Pregnancy resulted from rape or incest
o Continuation of pregnancy is likely to result in the birth of child with severe physical deformities
or mental retardation
Induced abortion
Elective (voluntary) abortion
o Interruption of pregnancy before viability at the request of the women, but not for reasons of
impaired maternal health or
fetal disease
Counseling before elective abortion
o Continued pregnancy with its risks & parental responsibilities
o Continued pregnancy with its risks & its responsibilities of arranged adoption
o The choice of abortion with its risks
Surgical techniques for abortion
Dilatation and curettage
o Performed first by dilating the cervix & evacuating the product of conception Mechanically scraping out of the contents (sharp curettage)
Vacuum aspiration (suction curettage)
Both
o Before 14 weeks, D&C or vacuum aspiration should be performed
o After 16 weeks, dilatation & evacuation (D&E) is performed Wide cervical dilatation
Mechanical destruction & evacuation of fetal parts
Surgical techniques for abortion
Dilatation and curettageo Hygroscopic dilators
: swell slowly & dilate cervix → cervical trauma can be minimized
o Laminaria tents
: stem of brown seaweed ( Laminaria digitata or japonica)
→ drawing water from proteoglycan complexes of cervix
→ dissociation allow the cervix to soften & dilate
Insertion technique : tip rests just at the level of internal os
Usually after 4-6hours, laminaria dilate the cervix sufficiently to allow easier mechanical dilation & curettage
May cause cramping pain
→ easily managed with 60 mg codeine every 3-4 hours
Surgical techniques for abortion
Technique for dilatation & curettage
o Remove laminaria → Uterus is sounded carefully to
Identify the status of the internal os
Confirm uterus size & position
o Further dilation of cervix with Hegar dilator
Surgical techniques for abortion
Complications : uterine perforationo 2 important determinants
Skill of the physician
Position of the uterus (retroverted)
o Small defects by uterine sound or narrow dilator
→ often heal without complication
o Suction & sharp curettage
→ Considerable intra-abdominal damage risk↑
→ Laparotomy to examine abdominal content (safest action)
o Other complications – cervical incompetence or uterine synechiae
Surgical techniques for abortion
Menstrual aspiration
o Aspiration of endometrial cavity using a flexible cannula and syringe within 1-3 weeks after failure
to menstruate
o Several points at early stage of gestation
Woman not being pregnant Implanted zygote may be missed by the curette
Failure to recognize an ectopic pregnancy
Infrequently, a uterus can be perforated
Surgical techniques for abortion
Laparotomy
o Abdominal hysterotomy or hysterectomy
o Indications
Significant uterine disease
Failure of medical induction during the 2nd trimester
Medical induction of abortion
Early abortion
o Outpatient medical abortion is an acceptable alternative to surgical abortion in women with
pregnancies of less than 49 days’ gestation
(ACOG, 2001b)
o Three medications for early medical abortion
Antiprogestin mifeprostone
Antimetabolite methotrexate
Prostaglandin misoprostol
Medical induction of abortion _
2nd trimester abortion
Medical induction of abortion
Oxytocin
o Successful induction of 2nd trimester abortion is possible with high doses of oxytocin administered
in small volumes of IV fluids
o Satisfactory alternatives to PG E2 for midtrimester abortion
o Laminaria tents inserted the night before Chance of successful induction is greatly enhanced
Medical induction of abortion
Prostaglandins
o Used extensively to terminate pregnancies, especially in the 2nd T PG E1, E2, F2α
o Technique
: Can act effectively on the cervix & uterus (86~95% effectiveness)
Vaginal prostaglandin E2 suppository & prostaglandin E1 (misoprostol)
As a gel through a catheter into the cervical canal & lowermost uterus
Injection into the amnionic sac by amniocentesis
Parenteral injection
Oral ingestion
Medical induction of abortion
Intra-amnionic hyperosmotic solutionso 20-25% saline or 30-40% urea injected into amnionic sac
→ stimulate uterine contraction & cervical dilatation
o Action mechanism : prostaglandin mediated ?
o Complications of hypertonic saline
Death
Hyperosmolar crisis (early into maternal circulation)
Cardiac failure
Septic shock
Peritonitis
Hemorrhage
DIC
Water intoxication
Hyperosmotic urea : less likely to be toxic
Medical induction of abortion
Antiprogesterone RU 486o Oral agent used alone in combination with oral PG to effect abortions in early gestation
o High receptor affinity for progesterone binding site
→ Block progesterone action
o Abortion rate
Single 600mg dose prior 6 weeks → 85%
Addition of oral, vaginal or injected PG → over 95%
o If given within 72 hours
Also highly effective as emergency postcoital contraception
Progressively less effective after 72 hours
o Side effects
Nausea, vomiting, & gastrointestinal cramping
Major risk → hemorrhage is a risk if abortion is incomplete
Medical induction of abortion
Epostane
o 3Я-hydroxysteroid dehydrogenase inhibitor
→ blocks the synthesis of endogenous progesterone
o Frequent side effect – nausea
o Hemorrhage is a risk if abortion is incomplete
Consequences of elective abortion
Maternal mortality
o Legally induced abortion
Relative safe during the first 2 months of pregnancy
( 0.6/100,000 procedures)
Doubled for each 2 weeks of delay after 8 weeks’ gestation
Consequences of elective abortion
Impact on future pregnancies
o Fertility : not altered by an elective abortion
o Vacuum aspiration for a first pregnancy
: Do not increase the incidence of
2nd trimester spontaneous abortions
Preterm delivery
Ectopic pregnancy
LBW infants
Consequences of elective abortion
Impact on future pregnancies
o Dilatations & curettage for a first pregnancy
: Increased risks for
Ectopic pregnancy
2nd trimester spontaneous abortions
LBW infants
o Multiple elective abortion : Not increased the incidence of preterm delivery & LBW infants
Placenta previa
→ increased following multiple sharp curettage abortion procedures
Consequences of elective abortion
Septic abortion Most often associated with criminal abortion
Metritis is usual outcome, but parametritis, peritonitis, endocarditis, and septicemia may
all occur Management
Prompt evacuation of products of conception
Broad-spectrum IV antimicrobials
Resumption of ovulation after abortion
o Ovulation may resume as early 2 weeks after an abortiono Therefore, if pregnancy is to be prevented,
effective contraception should be initiated soon after abortion