Micrognathia—prenatal ultrasonographic diagnosis

Inr. J. Gynaecol. Obstet., 1983,21: 343-345 International Federation of Gynaecology & Obstetrics

MICROGNATHIA-PRENATAL

ELIEZER Ultrasounda (Received (Accepted

SHALEVa,

EHUD WEINERa,

and Human Geneticb

ULTRASONOGRAPHIC

ESTER FELDMANa,

Sections,

Department

HANA COHENb

of Obstetrics

DIAGNOSIS

and HENRYK

and Gynecology

ZUCKERMANa

Central Emek Hospital,

Afula, Israel

March lst, 1982) September 7th, 1982)

Abstract Shalev E, Weiner E, Feldman E, Cohen H and Zuckerman H (Ultrasound and Human Genetic Sections, Department of Obstetrics and Gynecology, Central Emek Hospital, Afula Israel). Micrognathia-prenatal ultrasonographic diagnosis. Int J Gynaecol Obstet 21: 343-345, 1983 The first case of prenatal real-time ultrasonographic diagnosis of micrognathia is presented. Diagnosis was made at 17 weeks’ gestation in the fetus of a patient with previous infant affected with the syndrome of thrombocytopenia with absent radii (TAR). Recognition of micrognathia as a part of TAR syndrome and the easy visualization of fetal facial bones in the second trimester made diagnosis possible.

Key words: Micrognathia; Thrombocytopenia with absent radii; Ultrasound. Introduction Prenatal diagnosis of fetal structural abnormalities has become widespread with the introduction of diagnostic ultrasound. When an anomaly is fatal, pregnancy can be terminated, sparing the woman the carriage of a doomed fetus. In a condition compatible with life, a pediatrician can be alerted for immediate post natal intervention. Micrognathia (hypoplasia of the mandible 0020-7292/83/$03.00 0 1983 International Federation Printed and Published in Ireland

with recession of the chin) is the result of failure in the development of the first branchial arch. Micrognithia occurs in some systemic anomalies and sometimes has a hereditary characteristic. It may occur in a variety of as associated congenital malsyndromes, formations are not rare [ 31 . The ultrasonic prenatal diagnosis of micrognathia is presented in a case of a fetus with the syndrome of thrombocytopenia with absent radii (TAR). Case report A 25year-old Arabic woman, gravida 4, para 3, married to a first cousin, was admitted to the Gynecological Department at 13 weeks’ gestation because of vaginal bleeding. Her obstetrical history showed that the first and third pregnancies resulted in full term normal male infants. Her second pregnancy was terminated spontaneously at 28 weeks with a 1650-g male infant affected with TAR. Additional findings were: the infant had microcephaly, micrognathia, syndactyly, and a thoracic cave with eleven ribs. The premature newborn died 12 h after delivery with a massive pulmonary and adrenal hemorrhage. In the current pregnancy, examination with real time ultrasound (ADR model 2130) revealed an enlarged uterus with two gestational sacs. One of the sacs was empty and in the other was a viable fetus with crown-rump. “BPD” Int J Gynaecol

of Gynaecology

& Obstetrics

Obstet 21

344

Shalev et al.

and femur length corresponding to 13 weeks’ gestation. The humerus length corresponded to the gestational age, but the forearm bones were not visualized. The second examination at 17 weeks showed that the empty sac had almost vanished, fetal BPD, femur and humerus length corresponded to the calculated fetal age, and an elongated cyst of 10 mm X 20 mm in diameter was noted beneath the skull bone. An attempt to demonstrate forearms failed once again. In a sagital section of facial bones “absence” of the mandible was noted (Fig. 1). The parents were informed of the

possibility of an affected fetus and they decided to terminate the pregnancy. In addition profuse vaginal bleeding started and with augmented oxytocin infusion, the woman delivered spontaneously. First to come out was a mass of tissue with bloody clots, diagnosed histologically as a missed abortion, followed by a 200-g female infant. Examination of the aborted fetus revealed micrognathia, short forearms and deformed hands (Fig. 2). Bilateral absence of radii was noted on X-ray. On postmortem the presence of a simple cyst beneath the calvaria was confirmed and no other abnormalities were found except those mentioned above.

Fig. 1. Ultrasound sagittal scan through facial bones of fetus with micrognathia (A) and with normal mandible and maxilla (B), (b = brow, o = orbite, n = nasal bone, m = mandible). Int J Gynaecol Obstet 21

Ultrasound diagnosis ofmicrognathia

345

less often, dislocated hips, tibia1 torsion, dislocated patella, overriding fifth toe, rib and spine abnormalities, hypoplasia of mandible and maxilla [ 1 I . Although the hazard of fetal irradiation is recognized, fetal radiography was suggested as a means for screening the patient at risk of TAR, and real time ultrasound was used only to determine the fetal position and failed to reveal the anomaly [ 21 . The ultrasonic diagnostic problem is the tendency of the distal part of the upper limb to be very motile and to “hide” behind the fetal head. With the history of TAR syndrome, in cases where careful ultrasound search fails to reveal forearms, or when other associate anomalies are found, further radiologic investigation should be used for a positive diagnosis. If both methods fail, fetoscopy might be used, if available. Although micrognathia is not a constant feature in TAR syndrome and can be found in otherwise normal individuals, the recognition of micrognathia as a part of the syndrome made diagnosis possible. Fetal facial bones are easily visualized and the anomaly is therefore accessible to ultrasound diagnosis. FIN. 2. Full view of the aborted fetus showing micrognathia, short forearm and hands in varus position. Left thumb is attached to the hand by a thin pedicle.

Discussion TAR syndrome is very rare. It has an autosomal recessive pattern of inheritance with a recurrency risk of 1 in 4 (25%) for each offspring to be affected. The diagnostic criteria are thrombocytopenia of less than 100,000 platelets/mm3 and bilateral absence of a radius. Other skeletal abnormalities, recorded less often, may sometimes accompany TAR, such as: hypoplastic carpal and phalanges, short and malformed ulna, abnormal humerus, and even

References [Iall JG: Thrombocytopenia with absent radius. In Birth Defects, Atlas and Compendium (ed D Bergsma), p 843. The National Foundation - March of Dimes, Williams and Wilkins Co, Baltimore, 1973. Luthy DA, Hall JG and Graham CB: Prenatal diagnosis of thrombocytopenia with absent radii. Clin Genet 15: 495,1979. Warkany J: Congenital Malformations, Notes and Comments, Chap 70, p 621. Year Book Medical Publishers, Chicago, 1975. Address for reprints: Eliezer Shalev, M.D. Dept of Obstetrics and Gynecology Central Emek Hospital Afula, Israel

Int J Gynaecol Obstet 21