Department of Reproductive Science and Medicine, Imperial College School of Medicine at St Mary's Hospital, Mint Wing, South Wharf Road, London W2 INY, UK
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Abstract |
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Key words: intrauterine haematoma/pregnancy/recurrent miscarriage/ultrasound
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Introduction |
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A intrauterine haematoma (IUH) is a crescent-shaped echo-free area between the membranes and the uterine wall (Mantoni and Pedersen, 1981). IUHs, in the presence of a viable fetus, are occasionally reported as an incidental finding on ultrasound scans performed during supportive care and then reported to the clinicians. The significance of these haematomas is not clear. IUHs have previously been described in the literature in women presenting with threatened miscarriage. Some reports have suggested that they increase the risk of spontaneous miscarriage (Jouppila, 1985
; Borlum et al.1989
), the risk of intrauterine growth restriction (Mandruzzato et al.1989
) and preterm delivery (Borlum et al.1989
). However, other reports have refuted these findings (Stabile et al.1989
; Pedersen and Mantoni, 1990
). To our knowledge, the clinical significance of IUHs has not been assessed in a population of women suffering recurrent miscarriage.
The aim of this study was to establish the incidence and clinical significance of IUHs in the presence of a viable fetus in a recurrent miscarriage population.
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Materials and methods |
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The following information was recorded: age; history of previous miscarriages; presence of anti-phospholipid antibodies (Rai et al.1997); presence of an IUH; occurrence of vaginal bleeding; number of early pregnancy scans and pregnancy outcome. The patients were then divided into two groups according to the presence or absence of an IUH and the two groups compared. MannWhitney U- and
2-tests were used to statistically compare the groups. P values <0.05 were considered significant.
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Results |
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Table I shows there was no difference between the two groups in terms of age and number of previous miscarriages (P = not significant, MannWhitney U-test), or in the types of previous miscarriage (P = not significant,
2-test).
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Table II demonstrates that women with an IUH were scanned more frequently during the first trimester than those without an IUH. All women were first scanned at a median of 6 weeks gestation, although the interquartile range for women with an IUH was 56 weeks and for those without was 67 weeks. This was a statistically significant difference (P < 0.01, MannWhitney U-test).
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Discussion |
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Women with an IUH were more likely to be positive for anti-phospholipid antibodies. These patients receive thromboprophylaxis, according to our previously published protocol (Rai et al.1997), of aspirin from the time of a positive pregnancy test and heparin from the time of demonstration of an intrauterine pregnancy. This may contribute to the more frequent finding of a haematoma in these patients. However, this association had no effect on pregnancy outcome.
It is perhaps not surprising to find that women with haematomas are scanned more frequently during their supportive care, as the presence of a possible `abnormality' provokes anxiety in both patients and clinicians. In the light of the findings of this study, these extra scans are of doubtful clinical benefit. Both groups of patients received their first and last ultrasound scans at the same median gestation. However, statistically (see interquartile ranges), the IUH group were first scanned at a marginally earlier gestation. However, this statistical difference is unlikely to have contributed to the total number of scans performed during the first trimester.
The presence of an IUH in this group did not increase the risk of pregnancy loss at any gestation. This agrees with two previous studies (Stabile et al.1989; Pedersen and Mantoni, 1990
). However, unlike our study, these studies considered women presenting with threatened miscarriage so do not represent a similar group to ours. We also found no increased risk of pregnancy complications and no difference between the two groups in the number of live births. There was a possible trend towards preterm delivery at <32 weeks gestation in the haematoma group, which did not reach statistical significance (2/25 with an IUH, 2/169 without an IUH, P = 0.137,
2 with Yates correction). Larger numbers are required to increase the power of the study to assess this aspect further. An increased risk of preterm labour was previously described, but only in patients with haematomas presenting in the second trimester (Borlum et al.1989
). It has been suggested that the presence of blood within the uterus causes irritation and therefore stimulates contractions. However, in our study the haematomas disappeared spontaneously long before delivery, mostly by the end of the first trimester.
The data for this study were collected retrospectively so may be prone to bias. A larger prospective study is required to confirm the findings. Assessment of size and site of the lesion would be an interesting addition to such a study.
The ultrasound appearance of an IUH was first described almost 20 years ago in patients scanned between 1120 weeks gestation (Mantoni and Pedersen, 1981). It has been assumed to represent blood but there is no concrete evidence that this is the case. However, whatever this ultrasound appearance represents we can conclude that in this population it is not a poor prognostic factor for pregnancy outcome. As a result of this study we can now confidently offer reassurance to these women.
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Acknowledgements |
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Notes |
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References |
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Submitted on February 16, 2001; accepted on June 5, 2001.