Malpresentasi (Sungsang)

01Pathophysiology

By approximately 32-34 weeks of gestation, most fetuses spontaneously rotate into a cephalic (vertex) presentation because the head is the heaviest pole of the fetus and the lower uterine segment is narrowest. Breech presentation persists when this rotation fails to occur or is physically prevented.

Prematurity is the single most common association because the fetus simply has not yet completed spontaneous version at the time of delivery. In a premature fetus, the relative proportions of the head and body are different compared to term, and there is more amniotic fluid relative to fetal size, which allows for greater mobility and less impetus to "settle" head-down.

Uterine anomalies such as a bicornuate or septate uterus distort the cavity shape. The fetus cannot rotate freely because the available intrauterine space does not favor the normal longitudinal lie with head down. Similarly, placenta previa occupies the lower segment and physically blocks the head from engaging in the pelvis.

Polyhydramnios provides excessive room for fetal movement, allowing the fetus to remain in an unstable lie. Conversely, oligohydramnios restricts movement altogether, preventing the fetus from completing version. Both extremes of amniotic fluid volume, through opposite mechanisms, converge on the same outcome.

The clinical significance of breech lies in the risk during vaginal delivery. In a cephalic presentation, the head (the largest and least compressible part) delivers first and dilates the birth canal for the body. In a breech delivery, the body delivers first through an incompletely dilated cervix. The aftercoming head can then become trapped, because the cervix was only dilated enough for the smaller trunk, not the larger head. This is the central danger of breech vaginal delivery and the primary reason cesarean section is preferred.

02Classification and Clinical Manifestation

Frank breech is the most commonly tested type and the only type even considered for vaginal delivery in select guidelines. The distinction between these types is clinically important because the risk of cord prolapse increases as the presenting part becomes smaller and less able to occlude the pelvic inlet. On vaginal examination during labor, palpating the sacrum and ischial tuberosities suggests frank breech, while palpating small parts (toes) suggests footling breech.

03Diagnostic Workup

Leopold maneuvers are the best initial clinical tool and should raise suspicion. During the third maneuver (Pawlik grip), the examiner grasps the presenting part above the symphysis pubis. In a breech presentation, the presenting part is soft, irregular, and not ballottable, which is in contrast to the hard, round, ballottable head felt in a cephalic presentation. Fetal heart tones auscultated above the umbilicus further support breech lie, whereas in cephalic presentations heart tones are typically heard below the umbilicus.

Ultrasound is the confirmatory study and should be performed whenever breech is suspected on clinical exam. It defines the exact type of breech (frank vs. complete vs. footling), estimates fetal weight, evaluates amniotic fluid index, identifies the placental location, rules out cord presentation, and screens for fetal anomalies that may themselves be contributing to the malpresentation. Ultrasound is also essential before any attempt at external cephalic version to confirm candidacy and assess safety.

A common exam pitfall is confusing the breech buttocks with the face on vaginal exam. The key discriminator: the ischial tuberosities and sacrum form a bony triangle, whereas the face has the mouth and malar eminences. Additionally, meconium on the examining finger can occur from pressure on the breech but should not be confused with fetal distress in this context.

04Management and Treatment

External Cephalic Version (ECV)

ECV is the next best step for a patient at or beyond 37 weeks with a confirmed breech presentation and no contraindications. The procedure involves applying external pressure on the maternal abdomen to rotate the fetus from breech to cephalic. It is performed in a setting where emergency cesarean delivery is immediately available.

Prerequisites for ECV: A reactive nonstress test before the procedure, adequate amniotic fluid, and a reassuring fetal status. Tocolysis with terbutaline 0.25 mg subcutaneously is administered to relax the uterus and improve success. Rh-negative mothers must receive anti-D immunoglobulin (RhoGAM) after the procedure due to the risk of fetomaternal hemorrhage.

Contraindications to ECV include placenta previa, nonreassuring fetal status, ruptured membranes, multiple gestation, uterine anomalies, prior classical (vertical) cesarean scar, and significant vaginal bleeding. Any condition that would independently require cesarean delivery makes ECV unnecessary.

Cesarean Delivery

When ECV fails or is contraindicated, planned cesarean delivery at 39 weeks is the standard of care. This recommendation is grounded in the Term Breech Trial, which demonstrated that planned cesarean delivery for term breech reduces perinatal mortality and serious neonatal morbidity compared to planned vaginal breech delivery. On exams, cesarean delivery is almost always the correct answer for persistent breech at term.

Head Entrapment

If vaginal breech delivery is attempted or occurs precipitously, the dreaded complication is entrapment of the aftercoming head. Management includes Mauriceau-Smellie-Veit maneuver (the fetal body is placed over the operator's forearm, two fingers are placed on the maxilla to flex the head, and the other hand applies suprapubic pressure) or, if this fails, Piper forceps applied to the aftercoming head. Duhrssen incisions (cervical incisions at 2, 10, and 6 o'clock) may be used as a last resort for a trapped head through an incompletely dilated cervix.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students miss breech questions is by selecting vaginal delivery when the answer should be cesarean. Unless the vignette explicitly states frank breech, estimated fetal weight between 2500-3500 g, adequate pelvimetry, and an experienced operator, the answer is cesarean delivery. Exams rarely construct a scenario where vaginal breech delivery is correct.

Another frequent trap involves timing of ECV. Students sometimes choose ECV at 34-35 weeks. The correct timing is 37 weeks, because if a complication occurs (abruption, nonreassuring tracing), the fetus is at a viable gestational age for delivery without the risks of late prematurity. Choosing ECV too early also has a higher reversion rate (the fetus can flip back to breech).

Watch for vignettes describing a patient in labor with a "soft, irregular presenting part" and sudden fetal bradycardia. This is a footling breech with cord prolapse, and the answer is emergent cesarean with manual elevation of the presenting part off the cord (not ECV, not vaginal delivery, not oxytocin augmentation).

A subtle pearl: if a vignette describes breech presentation at 34 weeks with no labor, the answer is expectant management, not ECV. Many fetuses will spontaneously convert to vertex between 34 and 37 weeks. Intervening too early is a distractor designed to test whether you know that ECV is a term procedure.

Finally, always remember that an Rh-negative mother undergoing ECV must receive RhoGAM. This is a commonly tested association that links maternal-fetal medicine with immunology and is easy to overlook when focusing on the procedural aspects of version.