Compound Presentations: Rare Obstetric Events
Compound presentations are rare obstetric events and often engender much anxiety in the care team. Such concerns are usually unjustified, but considering the unlikely possibility of a problem delivery is valuable. Although in an average delivery service of 2500 births annually such an event might be expected to occur only about once a year, providers should know strategies for managing this situation if intervention becomes necessary. [1, 2]
Compound presentations may be observed more commonly after premature rupture of membranes, with preterm labor, with pelvic masses displacing the main fetal pole, or after inductions of labor involving floating presenting parts. Compound presentations are more likely with obstetric interventions than with spontaneous events. [3, 4] This type of presentation involves the prolapse of an extremity along with the more traditional presenting part, almost always the fetal vertex. Usually, the misplaced part is a hand or arm. Less commonly, a foot can present with the vertex if the baby is extended at the knee and flexed at the hip, or a hand or arm may present along the side of the breech. Management of these individual events differs according to the finding and the circumstances. If intact membranes are found, leaving them intact while resolution of the compound presentation is attempted may be wise.
The discovery of a hand beside the head is the most common presentation irregularity and is the least worrisome of the possibilities. In general, if left unattended, the hand will retract or the arm will extend further as labor progresses. Although the presence of an extremity usually does not create prohibitive dystocia, its absence is preferable in principle; this avoids circulatory compromise that could occur if the extremity is in place too long.  Also, the bruising to which the limb is prone adds undue concern for the parents until it disappears. If the hand has not prolapsed beyond the presenting part, causing the hand to retract often is accomplished, if necessary. In contrast, if the hand or arm has prolapsed past the presenting part, abandoning vaginal delivery and proceeding to cesarean delivery is wise.
Resolution is best accomplished by the baby itself. Although people sometimes forget that unborn children have all their reflexes in utero, unborn babies are fully capable, within the limitations of the space available, of reacting as they would as newborns. The simplest approach, therefore, may be to apply a benign noxious stimulus, such as a gentle pinch to a fingertip of the advancing hand. By applying a benign noxious stimulus (between contractions, of course), the hand may withdraw and never appear in the undesired position again. Less often, gentle pressure upward also may displace it successfully. If these maneuvers do not succeed in solving the abnormal situation, it can be ignored as long as labor is progressing normally. Excessive force applied to the extremity can injure it, or it may displace the head and convert the benign situation into an undeliverable shoulder presentation with entrapment of the fetus.
An intrusive foot beside the head is a more complicated event because it has more bulk than a hand and may retract less readily. Although it will not prolapse further, it may persist, increasing the diameter of the presenting part. Resolving this also involves trying a noxious stimulus, but this succeeds less often because of the complexity of the withdrawal response within available space. Forceful upward displacement also may not succeed if, for any reason, the knee does not readily bend or the hip does not flex further. An experienced operator may find that external manipulation of the leg may be achieved if it is the anterior one, but it is unreachable if it is the posterior limb. With fortuitous fetopelvic proportionality, delivery can still occur, but prudence precludes labor stimulation or difficult operative pelvic maneuvers. If vaginal birth is planned, it should occur spontaneously. Compound presentations preclude forceps applications orvacuum extraction.
Compound presentation with breech birth is less common, and management is less controversial. In general, unless readily resolved by benign maneuvers as described above, abdominal delivery is chosen even if it was not planned already for the breech presentation. An arm presenting with the breech may preclude descent of the breech into the pelvis, may add unduly to the increasing diameters presented as labor progresses, and may influence the baby to rotate into an arm or shoulder presentation. A case of a child with isolated lower brachial plexus palsy (Klumpke) and Horner syndrome who had a vertex compound arm presentation at birth has been reported. 
As suggested, in most cases, these events need not greatly influence the plans already made for the route of management of the birth process. Simple stimuli designed to get the child to withdraw the abnormal part may succeed. Management of labor and delivery after discovery of the intrusive part should be conservative and compatible with otherwise traditional obstetric principles.