OBSTETRICS OSCE REVIEWER

egpt2010

Internal Examination

DilatationEffacement

Clinical Pelvimetry

Inlet Diagonal conjugate:sacral promontory not accessible >11.5 cm

Midpelvis Ischial spines not prominentPelvic sidewalls not convergentSacrum curved

Outlet Intertuberous diameter >8 cmSubpubic arch >90°

Adequate Pelvis

Pelvic Inlet

Midpelvis

Pelvic Outlet

Partograph

Arrested by sedation and conduction analgesia

Cardinal movements of labor

DystociaProblem NULLIPARA MULTIPARA Management

Prolonged latent phase > 20 h > 14 h Rest

Protracted active phase dilation < 1.2 cm/hr < 1.5 cm/hr Expectant and support

(2°) arrest of dilation No Δ in >2 h (4 cm dilated, 180 MVU, no cervical change)

Same as nulli If with CPD, CSIf no CPD, oxy

Protracted descent <1 cm/hr <2 cm/hr Expectant and support

Arrest in descent No Δ in >1 h Same as arrest

Failure of descent >1 h with no descent in deceln. phase or 2nd stage

Same as nulli Same as arrest

Prolonged deceleration phase >3 h >1 h Same as arrest

Electronic Fetal Monitoring

BFHRVariability

AccelerationsDecelerations

Electronic Fetal Monitoring

• Normal BFHR = 110-160

• Variability– Minimal: fluctuations of 5 bpm– Moderate: 6-25 bpm– Marked/Saltatory: > 25bpm

• Accelerations (2 or more)– At least 15 bpm x 15 sec-2 min in term (20 min strip)– At least 10 bpm x 10 sec in preterm (20-30 min strip)

Electronic Fetal Monitoring

• Decelerations (decrease 15 bpm, > 30 sec)– Early: head compression– Variable: cord compression (abrupt decrease)– Late: uteroplacental insufficiency– Prolonged: >2 but <10 min

3 cm/min.

1 minute

1cm/min.

Montevideo units are calculated by subtracting the baseline uterine pressure from the peak contraction pressure for each contraction in a 10-minute window and adding the pressures generated by each contraction. In the example shown, there were five contractions, producing pressure changes of 52, 50, 47, 44, and 49 mm Hg, respectively. The sum of these five contractions is 242 Montevideo units.

Montevideo Units

Cardinal Movements of Labor

• Engagement– biparietal diameter passes through the pelvic inlet

• Descent

• Flexion– results from descending head meeting resistance

(cervix, walls of pelvis, pelvic floor)– chin is brought closer to the fetal thorax– shorter suboccipitobregmatic diameter is substituted

for the longer occipitofrontal diameter

Cardinal Movements of Labor

• Internal rotation– occiput gradually moves anteriorly toward the symphysis

pubis (or less commonly, posteriorly toward the hollow of the sacrum)

• Extension– base of the occiput in direct contact with inferior margin of

the symphysis pubis– progressive distension of the perineum and vaginal

opening increasingly larger portion of the occiput gradually appears

– head is born as the occiput, bregma, forehead, nose, mouth, and finally the chin pass successively over the anterior margin of the perineum

Cardinal Movements of Labor

• External rotation– delivered head undergoes restitution

• if the occiput was originally directed toward the left, it rotates toward the left ischial tuberosity; if it was originally directed toward the right, the occiput rotates to the right

– followed by completion of external rotation to the transverse position– rotation of the fetal body – one shoulder is anterior behind the symphysis and the other is

posterior

• Expulsion– anterior shoulder appears under the symphysis pubis, and the

perineum soon becomes distended by the posterior shoulder– after delivery of the shoulders, the rest of the body quickly passes

Cardinal Movements of Labor

Asynclitism

Type Anterior asynclitism Posterior asynclitismParietal bone Anterior PosteriorSagittal suture Posterior Anterior

Asynclitism

Active Management of the Third Stage of Labor

AMTSL

1. As soon as baby is out and you are sure there is no second baby, infuse oxytocin.

2. Apply controlled cord traction and suprapubic countertraction.

3. When placenta is at introitus, slowly rotate 360°.

4. Inspect placenta and membranes.5. Massage the uterus.

Instrument Identification

Rampley dressing forceps Foerster sponge holding forceps

Grave vaginal speculum Pederson vaginal speculum

Halsted Mosquito Micro ForcepsStraight / Curved

Kelly ForcepsStraight / Curved

Crile ForcepsStraight / Curved

Simpson Obstetrical Forceps Kielland Obstetrical Forceps

Piper Obstetrical Forceps

Pestalozza Obstetrical Curette

Backhaus towel forceps

Pudendal Nerve Block

• sensory innervation to the perineum, anus, and the more medial and inferior parts of the vulva and clitoris

• derived from ventral branches S2-S4• passes beneath the posterior surface of the

sacrospinous ligament just as the ligament attaches to the ischial spine– courses between the piriformis and coccygeus muscles – exits through the greater sciatic foramen in a location

posteromedial to the ischial spine– courses along obturator internus muscle within the

pudendal canal (Alcock canal), which is formed by splitting of the obturator fascia

Pudendal Nerve

• three terminal branches in the perineum:– dorsal nerve of the clitoris supplies the skin of the

clitoris– perineal nerve serves the muscles of the anterior

triangle and labial skin– inferior rectal branch supplies the external anal

sphincter, the mucous membrane of the anal canal, and the perianal skin

Pudendal Nerve

Knot Tying

Two-handOne-hand

Instrument