CASE REPORT

Not assuming the obvious: failed surgical terminationof pregnancy and multiple fetal abnormalities

Alyson Huntera,*, Helen Porterb, Phillipa Kylea

Case report

A 22 year old woman had an unplanned pregnancy

when she conceived unexpectedly at the end of taking a

depot progestogen for contraception (medroxyprogesterone

actetate). She had no previous medical history of note, did

not smoke or drink alcohol or take illegal drugs. There was

no known history among her own, or her partner’s rela-

tives, of congenital abnormality. She decided not to con-

tinue the pregnancy and at the time of her visit to the

Pregnancy Advisory Service an ultrasound scan confirmed

a singleton pregnancy of seven weeks and five days

gestation. No obvious abnormality in the fetus was noted

by ultrasound at this early stage. A suction termination of

pregnancy was arranged for 11 weeks of gestation. Mife-

pristone was given to soften the cervix and the suction

termination was undertaken without any apparent com-

plication. After the operation, she was prescribed, at her

request, another injection of medroxyprogesterone acetate.

Six weeks later, she experienced one day of vaginal

bleeding and, as she still felt pregnant, returned to the

Pregnancy Advisory Service. The scan at the clinic con-

firmed a continuing pregnancy with a biparietal diameter

consistent with the gestational age of 17 weeks. She

decided at this stage that she would probably continue with

the pregnancy but as concerns were raised regarding

potential complications secondary to the surgical proce-

dure, she was referred for a fetal medicine assessment.

The detailed ultrasound scan was performed at 19 weeks

of gestation. There were gross abnormalities in the fetus,

which had dolicocephaly, nuchal thickening of 8.8 mm, a

very abnormal chest with no obvious calcified ribs, enlarged

lungs and a tiny heart (Fig. 1(a)), severe ascites and oligo-

hydramnios. Although no major limb abnormalities were

noted, no movements were observed in the fetus throughout

the time of the scan. In view of these findings and the poor

prognosis, the woman decided to proceed to mifepristone/

misoprostol-induced termination of pregnancy. After deliv-

ery, she consented to postmortem examination of the fetus.

The placenta was sent for chromosomal analysis and

showed a normal female karyotype.

Postmortem examination showed a female fetus that was

appropriately grown for gestation. There was hydrops

fetalis with subcutaneous oedema, most severe around the

neck, and ascites. Bilateral talipes and syndactyly of the

second, third, fourth and fifth toes in both feet were noted.

The heart was found to be small but structurally normal.

There was a stenosis in the lower trachea with absence of

the cartilage rings. Ribs were present but were poorly

calcified. The lungs were extremely large with indentations

on their pleural surfaces caused by the ribs (Fig. 1(b)). The

lungs showed normal lobulation but when cut the surfaces

were pale and solid in appearance. Histology confirmed

that the distal trachea was narrow and collapsed with

absence of cartilage and glands. The right and left main

bronchi were dilated but structurally normal. The lungs

showed appearances similar to a congenital cystic adeno-

matoid lesion. While the bronchi were normal, the air

spaces were found to be large, irregular and separated by

increased mesenchymal tissue. The placenta was normal in

size, morphology and histology.

At a follow up visit to discuss the postmortem findings,

she confirmed that both she and her mother had varying

degrees of syndactyly of the toes.

Discussion

After the tertiary centre scan at 17 weeks of gestation,

there was a strong suspicion that the abnormalities seen

were due to the effects of the suction termination of

pregnancy or the drugs (mifepristone and medroxyproges-

terone acetate) administered to the woman at this time.

However, the importance of postmortem examination is

illustrated by this case.

The results of the postmortem examination suggested

that the primary abnormality in the fetus was a functional

BJOG: an International Journal of Obstetrics and GynaecologySeptember 2002, Vol. 109, pp. 1069–1071

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aDepartment of Fetal and Maternal Medicine, St Michael’s

Hospital, Bristol, UKbDepartment of Perinatal Pathology, St Michael’s Hospital,

Bristol, UK

* Correspondence: Dr A. Hunter, Department of Fetal and Maternal

Medicine, St Michael’s Hospital, Bristol, UK.

stenosis and collapse of the distal trachea due to absence of

the cartilage rings in the tracheal wall. The dilated main

bronchi and pulmonary hyperplasia were secondary to the

tracheal obstruction causing excessive fluid retention by the

lungs. Hence, these hyperinflated lungs caused compres-

sion of the heart and venous return resulting in fetal

hydrops. Congenital tracheal stenosis may be associated

with complete absence (as in this case) or incomplete

formation of tracheal cartilage, secondary to failure of the

splanchnic mesenchyme to develop around the distal tra-

chea. The laryngotracheal tube was normal as the tracheal

epithelium is endodermal in origin.

Tracheal stenosis has been associated with pulmonary

agenesis and cardiac anomalies, and may occur secondary

to cervical mesenchymal field defects1,2. This pattern of

abnormalities has been described before as the congenital

high airways obstruction syndrome (CHAOS). A series of

four cases from California described ultrasound findings of

large, flattened lungs, inverted diaphragms and dilated

airways distal to the obstruction, fetal ascites and hydrops3.

None of the fetuses survived and, at postmortem, three had

laryngeal atresia and one tracheal stenosis. The character-

istic sonographic appearances of this condition do not

probably occur until the middle of the second trimester

and probably reflect fetal lung development and fluid

secretion. This is illustrated by a case report that describes

a woman with normal 8- and 14-week scans but an

abnormal 18-week anomaly scan4. The differential diag-

nosis of ultrasound findings of diffuse echogenic lungs

should also include tracheal stenosis and congenital cystic

adenomatous malformation5.

Syndactyly has not previously been described as part of

the CHAOS. This abnormality is probably unrelated to the

other findings and may be familial in view of the family

history in this case. Various types of inheritable syndactyly

have been reported in the literature, usually as isolated

findings and none have been reported in association with

features of the CHAOS6,7. At present, there is no known

genetic syndrome with features of tracheal stenosis and

syndactyly.

Tracheal development and separation of the toes is

complete before 11 weeks of gestation, so both these

abnormalities are unlikely to be related to the failed

termination of pregnancy, which was performed after this

time. Medroxyprogesterone acetate is rarely associated

with non-genital malformations, and teratology databanks

do not report any other cases associated with CHAOS-like

defects and progestogen exposure in early pregnancy. One

study did show an increased frequency of syndactyly in a

woman who had used medroxyprogesterone prior to or

during pregnancy. Teratogenic effects of mifepristone

appear mostly to affect the heart. As this drug was given

after 11 weeks of gestation, it could not have caused

syndactyly in this case and there are no previous reports

linking it to CHAOS-type abnormalities.

Abnormal ultrasound features seen after failed termina-

tion of pregnancy need to be followed up by postmortem

assessment, otherwise important information that may

affect the next pregnancy will not be available. Information

obtained at postmortem examination in this case shows that

the severely abnormal features are most likely spontaneous

and that the risk of recurrence is low in a future pregnancy.

References

1. Weber TR, Connors RH, Tracy TF. Congenital tracheal stenosis with

unilateral pulmonary agenesis. Ann Surg 1991;213:70– 74.

2. Brouard J, Voirin J, Laloum D, Venezia R. McKusick – Kaufman

syndrome and fatal congenital tracheal stenosis. Arch Pediatr 1988;

45:373.

Fig. 1. (a) Ultrasound image showing hyperinflated lungs (inside callipers)

and small, compressed heart (arrow). (b) Postmortem examination of

thorax and abdomen showing grossly inflated lungs (L).

CASE REPORT1070

D RCOG 2002 Br J Obstet Gynaecol 109, pp. 1069–1071

3. Hedrick MH, Ferro MM, Filly RA, Flake AW, Harrison MR,

Adzick NS. Congenital high airway obstruction syndrome (CHAOS):

a potential for perinatal intervention. J Pediatr Surg 1994;29:

271– 274.

4. Weston MJ, Porter HJ, Berry PJ, Andrews HS. Ultrasonographic

prenatal diagnosis of upper respiratory tract atresia. J Ultrasound

Med 1992;11:673– 675.

5. Shen-Schwartz S, Neish C, Hill LM. Antenatal ultrasound for fetal

anomalies: importance of perinatal autopsy. Paediatr Pathol 1989;

9:1.

6. Goldstein DJ, Kambouris M, Ward RE. Familial crossed polysyn-

dactyly. Am J Med Gen 1994;50:215– 223.

7. McKiernan MV, McCann JJ. Familial syndactyly type III — report of a

large pedigree. Clin Genet 1993;44:270– 271.

Accepted 9 April 2002

CASE REPORT 1071

D RCOG 2002 Br J Obstet Gynaecol 109, pp. 1069–1071