Address correspondence to Val Catanzarite, MD, PhD, Maternal-Fetal Medicine, Mary Birch Hospital for Women at Sharp Memorial Hospital, 8010 Frost Street, Suite M, San Diego, CA 92123-2788 Ph: 619-541-6880; Fax: 619-541-6899

Synonyms: Funic presentation, cord presentation.

Definitions: Cord or funic presentation denotes the finding by sonography or clinical examination of the umbilical cord interposed between the leading part of the fetus and the internal cervical os. Umbilical cord prolapse can be used synonymously, but usually denotes egress of the cord beyond the cervix, in advance of the leading part of the fetus, usually in the presence of ruptured membranes.

Prevalence: 12-25:10,000 pregnancies^1,2.

Etiology: Variable; see text.

Associated (and consequential) abnormalities: Funic presentation and umbilical cord prolapse are increased in frequency with malpresentation (breech and transverse), polyhydramnios, maternal pelvic deformities, uterine abnormalities such as myomata, multiple gestation, and low-lying placenta or marginal placenta previa³.

Differential diagnosis: Vasa previa.

Prognosis: Depends upon fetal condition at the time of diagnosis, status of the cervix, and appropriate intervention.

Recurrence risk: Low, unless there is a persistent causative factor, e.g.: maternal pelvic deformity or uterine myomata.

Management: Controversial for funic presentation with a closed cervix. Delivery, usually by cesarean section, is indicated for funic presentation diagnosed during labor or umbilical cord prolapse^4,5,6.

MESH Umbilical Cord ICD9 7624 CDC 7624.1

Introduction

Funic presentation is a condition in which the umbilical cord is interposed between the leading part of the fetus and the internal os of the uterine cervix. Funic presentation, even during early labor, is often not clinically suspected. When the cervix is minimally dilated, the cord may not be palpable on examination, and the fetal heart rate tracing is often normal or shows mild or moderate variable decelerations, a common and usually innocuous pattern. As labor progresses, umbilical cord compression associated with contractions causes increasingly severe variable decelerations. When membranes rupture, if the cord prolapses through the cervix, it is compressed with every contraction; severe variable decelerations and/or profound fetal bradycardia may occur. Umbilical cord prolapse constitutes an obstetric emergency with potential for fetal death^4,6.

Much more is known about umbilical cord prolapse than about funic presentation, since the former is a dramatically apparent clinical diagnosis and the latter is usually diagnosed by sonography in the asymptomatic patient. The rate of umbilical cord prolapse is much lower in the vertex presenting fetus than in the fetus with breech presentation or transverse lie; the overall risk in vertex presentation is quoted at 0.2 to 0.4%, in all breech presentations 3.5%, and in transverse lie or footling breech presentation, approximately 10%. The relative risk notwithstanding, because the fetal presentation during labor is vertex in 96-98% of patients, the total number of cases of umbilical cord prolapse is greater for vertex than non-vertex presentation³.

Here, we describe the sonographic diagnosis of incipient umbilical cord prolapse in a patient with vertex presentation in preterm labor.

Case report

The patient is a G₂, now _P1-1-0-2 admitted at 35 weeks" gestation with idiopathic preterm labor. At the time of admission, the cervix was 2 cm dilated and 80% effaced with a ballottable vertex presenting. The fetal heart rate tracing was reactive, and no decelerations were seen. The patient was having regular, painful contractions. Tocolytic therapy with terbutaline and then intravenous magnesium sulfate was instituted. The next morning, contractions recurred, and the cervix dilated to 3 cm at 80% effacement, with a bulging bag of waters and ballottable vertex presentation. There was no suspicion of funic presentation on exam, but the fetal heart rate tracing showed several moderate variable decelerations and a severe variable deceleration (fig. 1). Sonographic evaluation was requested.

Figure 1: Fetal heart rate tracing. A severe variable deceleration is present.

 A longitudinal view of the lower uterine segment is presented as figure 2. The ultrasound scan showed loops of umbilical cord between the vertex and the dilated internal cervical os, both on real-time and color-flow studies. Careful examination of the lower uterine segment and lower placental edge with real-time and color-flow techniques showed no evidence of vasa previa. The patient was given adjunctive terbutaline subcutaneously to maintain tocolysis while preparations were made for expeditious cesarean section. This was performed under spinal anesthesia without incident. The infant was a 2885g, Apgar 4/8 female. She had mild transient tachypnea but was off of oxygen within 48 hours and home within four days.

Figure 2: Longitudinal midline view of the uterus and cervix. The cervix is dilated 3.7 cm. Multiple loops of umbilical cord are demonstrated below the level of the fetal vertex.

Discussion

The first reported case of prenatal diagnosis of funic presentation or occult cord prolapse was in 1979, when Christopher, Spinelli, and Collins diagnosed funic presentation in two patients in the late mid- trimester with hourglass membranes and malpresentation of the fetus7. Subsequent reports have described diagnoses of funic presentation by means of transabdominal and transperineal sonography and, more recently, with the use of Doppler studies^8-12. Only one previously diagnosed case not associated with malpresentation has been documented. The patient reported by Hales and Weatney8 was seen at 37 weeks" gestation for abdominal pain and was found to have a fetus in vertex orientation with funic presentation. The fetal monitor tracing was not described; the patient was not in labor but was delivered by cesarean section due to concerns regarding cord prolapse.

Differential diagnosis

It is of paramount importance to differentiate funic presentation from vasa previa, and the sonographic differentiation may be quite difficult. If the umbilical cord insertion into the placenta is clearly demonstrable, and the placenta does not have a succenturiate lobe, then vasa previa is not possible. However, we have diagnosed cases of vasa previa by ultrasound in which the umbilical cord inserted into one lobe of the placenta, and large vessels connecting the larger placental mass to a smaller succenturiate lobe coursed directly over the internal cervical os WE have also seen a case in which an anterior low-lying placenta had a velamentous cord insertion into its lower margin, from which vessels crossed over the cervix, exited the membranes on the posterior wall of the uterus, and gave a sonographic appearance of multiple loops of umbilical cord filling the lower uterine segment simulating funic presentation.

The differentiation between funic presentation and vasa previa may be possible by means of filling the patient"s bladder and tilting her into Trendelenburg position; cord loops from funic presentation may move away from the cervix, whereas the vessels in vasa previa (since they run within the membranes) remain unchanged in this position. Transvaginal sonography may also be helpful in the differential diagnosis. Vasa previa is a dangerous condition, with a high likelihood of fetal death from exsanguination when the membranes rupture, and management must be carefully individualized.

Antepartum diagnosis

Pelosi¹² and Lange et al⁹ have advocated screening for funic presentation as a part of antenatal testing late in pregnancy. For example, Lange et al reported that 9 of 1,471 patients at or beyond 37 weeks" gestation had funic presentation. It resolved in one case, cord prolapse and fetal death occurred in one case and the remaining patients were delivered by cesarean section for malpresentation. All were confirmed to have funic presentation at the time of delivery. However, in their series, there was no mention of whether or not the cervix was dilated at the time of evaluation. Additionally, the fetus was in a non-vertex presentation in all of their cases. The authors favored intervention (delivery) in cases of persistent cord presentation, but this is controversial; it could be argued that careful external version could correct both the cord position and fetal malpresentation, and allow vaginal delivery.

Intrapartum diagnosis

The sonographic diagnosis of funic presentation during labor when the cervix is dilated is a different matter entirely. Funic presentation per se is seldom a true emergency while the membranes are intact. However, upon rupture of the membranes, umbilical cord compression and fetal distress are the rule. Few situations will strike fear into the heart of the obstetrician/gynecologist or radiologist in the same way as diagnosis of funic presentation with cervical dilatation in an office outside the hospital setting !

In principle, it should be straightforward to diagnose funic presentation during labor, if the presenting part is high and the condition is searched for by ultra¬sound. In the patient at or near term, with non-vertex presentation, in labor, the usual plan of management is cesarean section, so that the diagnosis would not impact treatment. Given the frequency of cord prolapse, it is surprising that funic presentation or occult cord prolapse is not diagnosed more often during labor. We have made the diagnosis by ultrasound in three other cases over the past five years; two of these cases were associated with malpresentation and one with twins.

Management

As discussed above, the management of funic presentation when the cervix is closed, prior to the onset of labor, is problematic. Hospitalization or delivery is the management plan advocated by Lange et al9. Fetal monitoring during fundal pressure to assess for cord compromise is espoused by Pelosi12, with consideration of delivery if fetal monitoring suggests umbilical cord compression. I would argue instead for consideration of external cephalic version in the non-vertex fetus with funic presentation in late pregnancy, followed by induction of labor. The cord position usually changes during version, and vaginal delivery without complications may be possible.

When funic presentation is diagnosed during labor in a nonvertex presentation, cesarean section is indicated. For patients diagnosed with a vertex fetus and funic presentation, two management options could, in theory, be considered. Barrett5 recently reported a series of patients with cord prolapse in whom funic replacement was attempted; the majority delivered vaginally. However, these patients were in advanced labor when prolapse occurred. For the patient with cervical dilatation of 80mm, or funic presentation with a second twin, it may be reasonable to try vaginal delivery in the operating room, and with a full team ready for cesarean section. Earlier in labor, the diagnosis of funic presentation affords the opportunity to perform a cesarean section under controlled conditions and avert the potentially disastrous situation of cord prolapse.

References

1. Barclay ML. Umbilical cord prolapse and other cord accidents, In: Sciarra JJ, ed. Gynecology and Obstetrics. Vol 2. Philadelphia, JB Lippincott; chap 78 pp 1-7, 1989.

2. Moir JC. Monro Kerr"s Operative obstetrics. London: Baili/Àre, Tindall and Cox p259, 1964.

3.Dildy GA, Clark SL. Umbilical cord prolapse. Contemp Obstet Gynecol 38:23-32, 1993.

4. Koonings PP, Paul RH, Campbell K. Umbilical cord prolapse: A contemporary look. J Reprod Med 35:690, 1990.

5. Barrett JM. Funic reduction for the management of umbilical cord prolapse. Am J Obstet Gynecol 165:654, 1991.

6. Katz Z, Shoham (Schwartz) Z, Lancet M et al,: Management of labor with umbilical cord prolapse: A 5-year study. Obstet Gynecol 72:278, 1988.

7. Christopher CR, Spinelli A, Collins ML. Ultrasonic detection of hourglass membranes with funic presentation. Obstet Gynecol 54:130, 1979.

8. Hales ED, Weatney LS. Sonography of occult cord prolapse. JCU 12:283-285, 1984.

9. Lange IR, Manning FA, Morrison I, et al,: Cord prolapse: is antenatal diagnosis possible? Am J Obstet Gynecol 151:1083-5, 1985.

10. Johnson RL, Anderson JC, Irsik RD, et al.: Duplex ultrasound diagnosis of umbilical cord prolapse. JCU 15:282-284, 1987.

11. Sakamoto H, Takagi K, Masaoka N, et al. Clinical application of the perineal scan: prepartum screening for cord presentation. Am J Obstet Gynecol 155:1041-3, 1986.

12. Pelosi M. Antepartum ultrasonic diagnosis of cord presentation. Am J Obstet Gynecol 162:599-601, 1990.