A C TA Obstetricia et Gynecologica Letters to the Editor
Table 2. Diagnostic performance with no false positives. 1
Sensitivity Specificity False positive rate False negative rate
96.2% 100% 0% 3.8%
(1580/1643) (456/456) (0/456) (63/1643)
Susan Peirce1,*, Alistair Ray1 and Grace Carolan-Rees2 Cedar, Cardiff University, and 2Cedar, University Hospital of Wales, Cardiff, UK *Corresponding Author: Susan Peirce E-mail: [email protected]
Table 3. Outcome frequency with 43 false positives.
Speculum +ve Diamine oxidase +ve ve Total
1537 43 1580
References 63 456 519
1600 499 2099
Table 4. Diagnostic performance with 43 false positives. Sensitivity Specificity False positive rate False negative rate
96.1% 91.4% 8.6% 3.9%
(1537/1600) (456/499) (43/499) (63/1600)
signs of intact membranes as false positive results so that the false negative rate calculated in this manner is 63/1600, or 3.9%. The diagnostic performance of the speculum examination in these two models is: sensitivity 96.1–96.2%, specificity 91.4– 100.0%, false positive rate 0.0–8.6% and false negative rate 3.8– 3.9%.
1. Ladfors L, Mattsson LA, Eriksson M, Fall O. Is a speculum examination sufficient for excluding the diagnosis of ruptured fetal membranes? Acta Obstet Gynecol Scand. 1997;76(8):739–42. 2. El-Messidi A, Cameron A. Diagnosis of premature rupture of membranes: inspiration from the past and insights for the future. J Obstet Gynaecol Can. 2010;32(6):561–9. 3. van der Ham DP, van Teeffelen ASP, Mol BWJ. Prelabour rupture of membranes: overview of diagnostic methods. Curr Opin Obstet Gynecol. 2012;24(6):408–12. 4. Neil PRL, Wallace EM. Is Amnisure useful in the management of women with prelabour rupture of the membranes? Aust N Z J Obstet Gynaecol. 2010;50(6): 534–8.
Reply: Prospective studies to show possible benefits with tests for rupture of membranes (ROM) in equivocal ROM are still missing
Sir We thank Dr Susan Peirce and colleagues for their interest in the unsolved problem of how to diagnose rupture of the membranes (ROM) as discussed in our article from 1997 (1). At the time of our study some hospitals in Sweden analyzed diamine oxidase (DAO) to determine the presence or absence of ROM. The aim of our study was to evaluate the false-negative rate by using a sterile speculum examination for the diagnosis of ROM. As there is no need to use tests for unequivocal ROM we focused on women with equivocal ROM. A speculum examination is easily performed. In women with suspected but not visualized ROM it might be of value to apply an additional test. We published all our data so it was possible to re-analyze the figures as Peirce et al. did (2). We did not use the DAO test in patients with visible ROM at speculum examination and the possible false negatives among these patients were not recorded.
We are convinced that a biochemical test is of no value and should not be used in cases with unequivocal ROM. For this reason we did not present our data as Peirce et al. did in their tables. We regret that we did not totally focus on women with equivocal ROM. Women with amniotic fluid visible at speculum examination and signs of intact membranes at delivery should not have been included in the analysis (n = 43). A new test for ROM should not be introduced as a commercial product before prospective studies have been carried out. These studies should be performed in women with suspected ROM in whom amniotic fluid could not be visualized at speculum examination. Provided such a test was used (and the result was blinded) and a raised morbidity could be demonstrated in the group with a positive test, it might indicate usefulness of the test. But to prove the benefit of the test a study should be performed where women with equivocal ROM were randomly allo-
ª 2013 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 92 (2013) 1115–1117
Letters to the Editor
cated to using the test or not. A lower morbidity in the group where the test was used would indicate an adequate test. We have not been able to find any studies designed as proposed above, yet there are commercial products on the market. This might indicate that it is possible to market a product even without proven benefit or that the potential benefit is so small that a proper study must include numerous patients to obtain an acceptable power. Lars Ladfors* and Lars- Ake Mattsson Department of Obstetrics and Gynecology, Sahlgrenska University € Hospital/Ostra, Gothenburg, Sweden
E-mail: [email protected]
References 1. Ladfors L, Mattsson LA, Eriksson M, Fall O. Is a speculum examination sufficient for excluding the diagnosis of ruptured fetal membranes? Acta Obstet Gynecol Scand 1997;76:739–42. 2. Peirce S, Ray A, Carolan-Rees G. Diagnostic reliability of sterile speculum exam for rupture of membranes. Acta Obstet Gynecol Scand. 2013;92:1116–1117.
*Corresponding Author: Lars Ladfors
To tamponade or not to tamponade?
Sir We read with great interest your series on the use of Bakri balloon tamponade for postpartum hemorrhage (PPH) and commend you for encouraging the use of this simple technique (1). We would like to share our data on 43 cases of massive PPH (>2000 mL) in which balloon tamponade was attempted between 2007 and 2012 at an inner city London hospital. In our own series of 43 women, Bakri balloon tamponade succeeded in abating hemorrhage in 93% of cases, obviating the need for hysterectomy. Of these, 14 women (32.6%) required an additional procedure, i.e. the combined “uterine sandwich” technique which is usually performed when tamponade alone fails to control bleeding (2); of these, two cases proceeded to hysterectomy (14.3%). Interestingly, 81.4% of our cases occurred following cesarean section and balloons were introduced via the abdominal route. Mean estimated blood loss for these 43 cases was 3400 mL and mean duration of the balloons remaining in situ was 22 h. The standard procedure at our institution is for inflation of the balloon with 350 mL saline. We would also like to highlight that intravaginal balloon tamponade is a useful tool in non-surgical management of severe vaginal lacerations: often when further sutures were attempted, the edematous vaginal tissues “cheese wired,” resulting in further vaginal trauma. Tattersall and Braithwaite (3) and Yoong et al. (4) alluded to the placement of one or two balloons in the vaNon-medical staff such as midwives should be trained in the use of this simple effective technique in order to prevent unnecessary delays in managing PPH should doctors become occupied elsewhere on the labor ward. This is demonstrated by Stitely and colleagues in their description of the effective use of a simulator to teach the procedure of inserting the Bakri balloon (5). While being effective and simple, a downside to the Bakri balloon is its cost, and other alternatives may be used, especially
in developing countries. Self-made condom catheters, Rusch catheters and Sengstaken-Blakemore tubes, although not designed for obstetric use, are cheaper and may be of more use to the obstetric practitioner in the resource-poor setting. A further alternative is the development of a cheaper device for uterine balloon tamponade, an initiative that is currently being developed by an international non-governmental organization: PATH. The organization is currently producing a prototype intended for pilot studies in Africa, India and South Asia over the next 3 years (6).
Alexander Nesbitt1,2, Nabita Rai1,2, Jhuma Limbu1,2, Isla Leslie1,2 and Wai Yoong1,2,* 1 University College London and Royal Free School of Medicine, and 2Department of Obstetrics and Gynaecology, North Middlesex University Hospital, London, UK *Corresponding Author: Wai Yoong E-mail: [email protected]
References 1. Gr€ onvall M, Tikkanen M, Tallberg E, Paavonen J, Stefanovic V. Use of Bakri balloon tamponade in the treatment of postpartum hemorrhage: a series of 50 cases from a tertiary teaching hospital. Acta Obstet Gynecol Scand. 2013;92(4):433–8. 2. Yoong W, Ridout A, Memtsa M, Stavroulis A, Aref-Adib M, Ramsey-Marcelle Z, et al. Application of a uterine
ª 2013 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 92 (2013) 1115–1118