ROLE OF ULTRASOUND IN OBSTETRIC EMERGENCY DR.SHREEDHAR VENKATESH PROF.&HOD OBSTETRICS AND GYNAECOLOGY

Pelvic pain and vaginal bleeding are two of the most common presenting complaints of women examined in the emergency department.

In addition to clinical history, physical examination, and laboratory data, sonography is essential in evaluating pelvic pain and vaginal bleeding in women of childbearing age because many causes of these two presentations have suggestive or definitive sonographic findings.

PREGNANCY OF UNKNOWN LOCATION (PUL)

HOW CAN ULTRASOUND ANSWER THE QUESTION?

DISCRIMINATORY ZONE

It refers to a defined level of hCG above which the gestational sac of an intrauterine pregnancy should be visible on ultrasound.

The concept of a discriminatory zone has limitations. Levels of hCG of 1000iu/l,1500iu/l and 2000iu/l have been used discriminatory zone.

These levels are dependent upon the quality of the ultrasound equipment, the experience of the sonographer, prior knowledge of woman’s risk.

For specialized units performing high resolution vaginal ultrasound with prior knowledge of the woman’s symptoms and serum hCG, a discriminatory zone of 1000iu/l can be used. In other units offering a diagnostic transvaginal scan without prior clinical or laboratory knowledge a discriminatory zone of 1500iu/l or 2000iu/l is acceptable

RCOG Guideline No.21,Evidence level III

DIFFERENT SCANNING MODALITIES

Gestational sac TAUS

GESTATIONAL SAC TVUS

3D Scanning

ENDOMETRIAL FINDINGS SUGGESTIVE OF UTERINE PREGNANCY

DOUBLE DECIDUAL SIGN

To distinguish between an early pregnancy intrauterine pregnancy and a pseudogestational sac

Consists of the decidua parietalis(that lining the uterine cavity) and decidua capsularis(lining the gestational sac)

ADNEXAE AND OVARIES

CORPUS LUTEUM

TUBAL ECTOPIC PREGNANCY

ADNEXAL MASS

ADNEXAL ECTOPIC PREGNANCY WITH POSITIVE CARDIAC PULSATION

INTERSTITIAL PREGNANCY

Cornual or interstitial,gestations account for as many as 3% of all ectopic pregnancies and carry a high mortality rate as a result of delayed rupture with extensive haemorrhage. Original sonographic descriptions include an eccentric intrauterine location and thinning of the surrounding myometrial mantle to less than 5mm.

Care must be exercised to avoid misinterpreting a normal intrauterine pregnancy in an anomalous uterus-such as separate or bicornuate uterus- as an interstitial pregnancy.

OVARIAN ECTOPIC

CERVICAL ECTOPIC

Bad prognosis-potential for uncontrollable haemorrhage Differentiate from an abortion in progression Round or oval non crenated sac , fetal cardiac activity, present, closed

internal os, constant sac shape and location on follow-up sonogram

CERVICAL ECTOPIC

HETEROTROPIC PREGNANCY

ABDOMINAL ECTOPIC

Peritoneal cavity free fluid or haemoperitoneum in the pouch of douglas.

Differentiated from- ruptured corpus luteum, appendicitis(negative beta hCG)

PERITONEAL FREE FLUID

RING OF FIRE SIGN OR RING OF VASCULARITY

Signifies a hypervascular lesion with peripheral vascularity on color or pulsed Doppler exmination of pelvis due to low impedance high diastolic flow.

Seen in highly vascular pelvic lesions like: Corpus luteum cystEctopic pregnancy

RETAINED PRODUCTS OF CONCEPTION

Retained products of conception after spontaneous or elective abortion or full term pregnancy may cause secondary post partum haemorrhage or may serve as nidus for uterine infection.

Predisposing factors include the presence of a succenturiate lobe or placenta accrete,increta, or percreta, preventing complete placental delivery. Sonographic findings include endometrial expansion of heterogenous echogenic material and focal areas of hyperechogenicity that may represent retained placental calcifications.

Retained trophoblastic tissue exhibits low-resistance arterial flow, which is uncommonly seen with endometritis.

RETROPLACNTAL HEMATOMA AND ABRUPTIO PLACENTA

Seperation of placenta from myometrium where it is implanted causes bleeding. When only the margin of the placenta is separated , its called marginal subchorionic hematoma.

When the bleeding is behind the placenta , it is termed as retroplacental bleed. The term abruption is typically reserved for premature placental separation occurring after 20 weeks.

Subamniotic bleeding is a collection anterior to the placenta and limited by umbilical cord.

SUBCHORIONIC HEMATOMA

RETROPLACENTAL HEMATOMA

Abruptio placenta is one of the most serious complications of pregnancy, accounting for upto 25% of perinatal deaths, Diagnosis requires a high degree of suspicion because the signs and symptoms are variable, including a painful tense uterus, vaginal bleeding, premature labor, fetal distress, and coagulopathy; most episodes remain asymptomatic. Sonographic findings are negative in most cases, either because of the passage of blood without accumulation behind the placenta or because of blood being isoechoic with the placenta. The only evidence of abruption may be the identification of an abnormally thick placenta. The sensitivity of the sonogram is low, 10-20%.

PLACENTA PREVIA

Routine ultrasound scanning at 20 weeks of gestation should include placental localization.

Transvaginal scans improve the accuracy of placental localization and are safe , so the suspected diagnosis of placenta previa at 20 weeks of gestation by abdominal scan must be confirmed by transvaginal scan.

In the second trimester TVS will reclassify 25-60% of cases where the abdominal scan diagnosed a low lying placenta,meaning fewer women will need follow up. In the third trimester, TVS changed the transabdominal scan diagnosis of placenta previa in 12.5% of 32 women. Leerentveld et al demonstrated high levels of accuracy of TVS in predicting placenta previa in 100 women suspected of having a low lying placenta in the second and third trimester.

MYOMETRIAL THICKENING

Measurement of the thickness of lower uterine segment in women who had a previous caesarean section and had a low lying anterior placenta or placenta previa by measuring between the bladder wall and retroplacental vessels, as seen by color Doppler.

All patients later proven to have placenta accrete had myometrium of less than 1mm , which was a predictive of accrete as lacunae.

TRANSLUCENCY ZONE

COLOR DOPPLER

SIGNS SUGGESTIVE OF PLACENTAL INVASION BY 3D DOPPLER

Numerous coherent vessels involving the whole uterine serosa-bladder junction

Hypervascularity Inseperable cotyledonal and intervillous circulations, chaotic branching,

detour vessels.

UTERINE DEHISCENCE AND RUPTURE

RED OR CARNEOUS FIBROID DEGENERATION

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