Case Of The Month -December 2005

Cervical Smear

Clinical Details

Post partum smear in 40 year old female

During a visit to Africa in 1998 the patient went swimming in Lake Malawi after which she became very sick with nausea and vomitting. She visited a tropical diseases centre in London who could not find any reason for her symptoms. On her return to New Zealand the symptoms persisted throughout 2 pregnancies. In November 2001 at her postnatal visit the patient complained of renal colic. A routine postnatal cervical smear was taken.

Cytologic Findings

On examination the smear showed several ova highly suggestive of Schistosoma haematobium.

Urine cytology and serological tests confirmed Schistosoma haematobium.

It was interesting to note that in the initial wet preps of the urine samples very few ova were able to be identified. Subsequently we made filter specimens and stained them with pap stain. Occasional ova were identified in the filter preparations.

Discussion

S. haemaobium is found principally in Africa. Freshwater snails are the intermediate host for the parasite. Motile forms of the organisms, called cercariae, are released in the water, penetrate through human skin causing "swimmer's itch", and usually lodge themselves in lymphatics of the pelvic organs, mainly the urinary bladder. The cercariae become mature worms and the female worms release the characteristic ova from which larval forms (miracidia) hatch and release into the water in urine or faeces. S.haematobium may invade the lymphatics of the uterus and deposit ova. Clinically the lesions of the uterine cervix may imitate cancer. In smears the ova have a thick, semi translucent shell with a terminal spine. The ova may vary in size with an average about 140 µm in length and 60-70 µm in width. The miracidia are boat-shaped organisms which resemble the ova but without the shell.

Reference: Diagnostic Cytology, Koss, Vol One, Third Ed, pg 258.

The first four photomicrographs show the ova of S. haematobium in the cervical smear. Several ova were found in the smear. Another feature was the marked inflammtory exudate including multinucleated histiocytes in the background. The last two pictures are the ova found in the urine sample which had been filtered and stained. Only two or three ova were seen in the urine.

While S. haematobium is a common finding in Africa it is not often seen or identified here and mostly the first diagnosis is made from a urine sample rather than a cervical smear.

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Thanks to Carol for submitting this case