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Clinical presentation and risk factors of placental abruption

Article in Acta Obstetricia Et Gynecologica Scandinavica · February 2006

DOI: 10.1080/00016340500449915 · Source: PubMed

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ORIGINAL ARTICLE

Clinical presentation and risk factors of placental abruption

MINNA TIKKANEN, MIKA NUUTILA, VILHO HIILESMAA, JORMA PAAVONEN & OLAVI YLIKORKALA

Department of Obstetrics and Gynecology, University Central Hospital, Helsinki, Finland Abstract

• Background. To study the risk factors of placental abruption during the index pregnancy. Methods. One hundred and ninety-

eight women with placental abruption and 396 control women were identified among 46,742 women who delivered at a tertiary referral university hospital between 1997 and 2001. Clinical variables were compared between the groups. Multivariate logistic regression analysis was applied to identify independent risk factors. The clinical manifestations of placental abruption were also studied. Results. The overall incidence of placental abruption was 0.42%. The independent risk factors were maternal (adjusted OR 1.8; 95% CI 1.1, 2.9) and paternal smoking (2.2; 1.3, 3.6), use of alcohol (2.2; 1.1, 4.4), placenta previa (5.7; 1.4, 23.1), pre-eclampsia (2.7; 1.3, 5.6), and chorioamnionitis (3.3; 1.0, 10.0). Vaginal bleeding (70%), abdominal pain (51%), bloody amniotic fluid (50%), and fetal heart rate abnormalities (69%) were the most common manifestations. Neither bleeding nor pain was present in 19% of the cases. Overall, 59% had preterm labor (OR 12.9; 95% CI 8.3, 19.8), and 91% were delivered by cesarean section (34.7; 20.0, 60.1). Of the newborns, 25% were growth

• restricted. The perinatal mortality rate was 9.2% (OR 10.1; 95% CI 3.4, 30.1). Retroplacental blood clot was seen by

ultrasound in 15% of the cases. Conclusions. Maternal alcohol consumption and smoking, and smoking by the partner turned out to be independent risk factors for placental abruption. Smoking by both partners multiplied the risk. The liberal use of ultrasound examination contributed little to the management of women with placental abruption. Key words: Placental abruption, placenta, risk factors Abbreviations: PPROM: preterm premature rupture of the membranes, PIH: pregnancy-induced hypertension, IUGR: intrauterine growth restriction

Placental abruption, defined as the complete or partial separation of the placenta before delivery, is a major cause of poor pregnancy outcome, which

• ften requires an emergency cesarean section and

intensive care of the newborn. Although the classic symptoms of placental abruption have been well described, the signs and symptoms may vary con- siderably (1). In recent studies the incidence of placental abruption has been 0.50.6% (24). The rates have been increasing in many countries (58). We have previously reported the sociodemo- graphic and historic risk factors for placental abrup- tion, i.e. risk factors preceding the index pregnancy (8). These included smoking, uterine malformation, history of cesarean section, and history of placental

• abruption. In this study we wanted to define the risk

factors appearing during pregnancy and to describe the clinical manifestations of placental abruption at the time when ultrasound examination is routinely used in obstetrical practice. Methods We sought all patients with a diagnosis of placental abruption (ICD-10 O45.0, O45.8, O45.9) among a total of 46,742 deliveries during 19972001 in our university hospital which serves a population of 1.2 million. Women delivering after 22 weeks of gestation or having a newborn weighing more than 500 g were included in the analyses. The duration of

Correspondence: Olavi Ylikorkala, Department of Obstetrics and Gynecology, University Central Hospital, 00029 Helsinki, Finland. E-mail:

• lavi.ylikorkala@hus.fi

Acta Obstetricia et Gynecologica. 2006; 85: 700705

(Received 7 June 2005; accepted 28 October 2005)

ISSN 0001-6349 print/ISSN 1600-0412 online # 2006 Taylor & Francis DOI: 10.1080/00016340500449915

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the gestation calculated from the last menstrual period was confirmed or corrected based on ultra- sound screening examination performed at 1113

• weeks. The patients also underwent another routine

screening ultrasonographic examination at 1820 weeks. We systematically recorded from the hospital charts relevant clinical data, presenting symptoms and signs, and placental findings. The diagnosis of placental abruption was made on clinical judgment and findings on ultrasound examination, and was confirmed by the presence of one or more of the following: retroplacental adherent hematoma, marks

• f Couvelaire uterus, or blood clot detected at

cesarean section. The control group consisted of the next women who gave birth before and after each index case, and who had no evidence of placental abruption. The potential risk factors related to the course of the index pregnancy included in the analyses were defined as follows. Assisted conception referred to patients who had undergone ovulation induction, intrauterine insemination, standard in vitro fertiliza- tion, or intracytoplasmic sperm injection. Smoking habits of the women and their partners and alcohol consumption of the women were sys- tematically recorded at the first antenatal clinic visit. All women and their partners who smoked at least

• ne cigarette per day were defined as smokers.

Women who used more than two doses of alcohol per week were defined as alcohol users. First trimester bleeding was defined as bleeding before the 12th completed gestational week. Second trimester bleeding was defined as bleeding between the 12th and 28th gestational weeks, and third trimester bleeding as bleeding after the 28th week not immediately associated with placental abruption. Birth before 37 completed gestational week was defined as preterm. Placental localization was re- corded during the screening ultrasound examination at 1820 weeks of gestation and those with suspicion

• f placenta previa were followed and re-examined

during the third trimester. Chronic hypertension was defined as blood pres- sure ]

/140/90 mmHg before pregnancy or before

the 20th week of gestation. Pregnancy-induced hypertension (PIH) was diagnosed if systolic blood pressure had increased by more than 30 mmHg or diastolic blood pressure by more than 15 mmHg after the 20th gestational week exceed- ing 140/90 mmHg, in the absence of proteinuria (B

/0.3 g/l). Pre-eclampsia was defined as PIH with

proteinuria (]

/0.3 g/l).

Acute chorioamnionitis was defined on the basis

• f symptoms including maternal fever of ]

/388C,

increased heart rate of the mother and the fetus, uterine tenderness, foul odor of the amniotic fluid, increased blood white cell count, and increased C-reactive protein concentration. Preterm prema- ture rupture of the membranes (PPROM) was defined as a spontaneous rupture of the membranes before 37 completed gestational weeks. PPROM lasting more than 24 h before delivery was consid- ered prolonged. Intrauterine growth restriction (IUGR) was defined as birth weight under the 10th percentile of the national standard. Categorical data were analyzed by Chi-square test and Fisher’s exact probability test. To compare continuous variables, Student’s t-test was applied for normal distributions, and MannWhitney U-test for other distributions. A multivariate logistic regres- sion analysis was performed with placental abruption as the dependent variable and selected features of the index pregnancy as independent variables. Results We identified 198 women with placental abruption giving an overall incidence of 0.42%. Nine case women and eight control women delivered twins (Table I). Thus, there were a total of 207 newborns among the cases and 404 newborns among the

• controls. Characteristics of the study population

have been reported (8). Briefly, compared to control women, women with placental abruption were sig- nificantly more often older than 35 years, had lower educational level, were more often unmarried, more

• ften had three or more deliveries, more often had

uterine malformation, history of cesarean section, and history of placental abruption. Placental abruption was classified as total in 13 cases (7%) and partial in 185 cases (93%). Overall, 117 (59%) of the case women delivered preterm, compared to 40 (10%) of the control women (OR 12.9, 95% CI 8.3, 19.8). Of the case women, 180 (91%) delivered by cesarean section compared to 95 (24%) of the control women (OR 34.7, 95% CI 20.0, 60.1). Of the newborns with placental abruption, 51 (25%) were growth restricted com- pared to 16 (4%) of the control babies (OR 7.9, 95% CI 4.4, 14.3). Ten infants (4.8%) died in utero, as compared with 2 infants (0.5%) in the control group. The perinatal mortality rate was 9.2% (19 of 207), as compared with 1% (4 of 404) in the control group (OR 10.1, 95% CI 3.4, 30.1). Univariate analyses showed that, compared to the controls, the case women (OR 2.1, 95% CI 1.4, 3.3) and their partners (OR 2.3, 95% CI 1.4, 3.6) more Clinical presentation and risk factors of placental abruption 701

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• ften were smokers through the pregnancy. If both

partners were smokers, the risk for placental abrup- tion was 4.8-fold (95% CI 2.2, 10.0). After antenatal clinic counseling, only 11% of the smoking women stopped smoking during pregnancy. Case women also drank alcohol more often (OR 2.6, 95% CI 1.3, 5.0). Other risk factors associated with placental abruption were vaginal bleeding during the second (OR 2.4, 95% CI 1.3, 4.4) or third trimester (OR 2.5, 95% CI 1.1, 5.6), placenta previa (OR 6.2, 95% CI 1.7, 23.3), pre-eclampsia (OR 2.7, 95% CI 1.3, 5.4), and chorioamnionitis (OR 3.3, 95% CI 1.1, 10.2) (Table II). We then performed a multivariate logistic regres- sion analysis of all variables associated with placental abruption by univariate analyses. In the adjusted analyses, maternal smoking (OR 1.8; 95% CI 1.1, 2.9), paternal smoking (OR 2.2; 95% CI 1.3, 3.6), use of alcohol (OR 2.2; 95% CI 1.1, 4.4), placenta previa (OR 5.7; 95% CI 1.4, 23.1), pre-eclampsia (OR 2.7; 95% CI 1.3, 5.6), and chorioamnionitis (OR 3.3; 95% CI 1.0, 10.0) remained independently associated with placental abruption (Table II). The clinical manifestations of placental abruption are shown in Table III and Figure 1. Placental abruption occurred before labor in 146 (74%) cases and during labor in 52 (26%) cases. Vaginal bleeding was present in 138 (70%), abdominal pain, uterine tenderness, uterine tetanic contractions or hyper- tonic uterus in 100 (51%) cases, and bloody amniotic fluid in 93 (50%) cases. Fetal heart rate abnormalities (bradycardia, repetitive late decelera- tions, or decreased beat-to-beat variability) were present in 137 (69%) cases. Retroplacental blood clot was seen by ultrasound in 30 (15%) cases. Decreased fetal movements were reported in 22 (11%) cases. Seventy-nine percent of the infants were born within 24 h after the first symptoms of placental abruption, and 24% were born in less than

• ne hour.

Discussion We studied the risk factors present during the index pregnancy and the clinical manifestations of placen- tal abruption. In the adjusted analyses, maternal and paternal smoking, use of alcohol, placenta previa, pre-eclampsia, and chorioamnionitis were signifi- cantly associated with placental abruption. This

Table I. Selected characteristics related to the course of the index pregnancy Variable Cases Controls p-value n

/198

n

/396

• No. (%)
• No. (%)

Assisted conception 13 (6.6) 24 (6.1) 0.8 Behavioral Smoking by Woman 50 (25.3)a 54 (13.6)* 0.0004 Partner 40 (20.2) 40 (10.1) 0.0007 Both 22 (11.1) 10 (2.5) B

/0.0001

Alcohol consumption 20 (11.0) 18 (4.6) 0.004 Pregnancy complications Bleeding I trimester 16 (8.1) 22 (5.6) 0.2 Bleeding II trimester 22 (11.1) 20 (5.1) 0.006 Bleeding III trimester 13 (6.6) 11 (2.8) 0.03 Placenta previa 9 (4.5) 3 (0.8) 0.002 Chronic hypertension 9 (4.5) 19 (4.8) 0.9 PIH 18 (9.1) 22 (5.6) 0.1 Pre-eclampsia 19 (9.6) 15 (3.8) 0.004 Maternal diabetes Type I or II 2 (1.0) 6 (1.5) 0.7 Gestational 18 (9.1) 43 (10.9) 0.5 Prolonged PPROM 10 (5.1) 10 (2.5) 0.1 Chorioamnionitis 8 (4.0) 5 (1.3) 0.03 Twin pregnancy 9 (4.5) 8 (2.0) 0.08

aBoth groups include 11 single mothers.

Table II. Risk factors for placental abruption Univariate Multivariate (adjusted) Variable OR (95% CI) OR (95% CI) Maternal smoking 2.1 (1.4, 3.3) 1.8 (1.1, 2.9) Paternal smoking 2.3 (1.4, 3.6) 2.2 (1.3, 3.6) Use of alcohol 2.6 (1.3, 5.0) 2.2 (1.1, 4.4) Bleeding in 2nd or 3rd trimesters 2.1 (1.2, 3.6) 1.7 (0.9, 3.0) Placenta previa 6.2 (1.7, 23.3) 5.7 (1.4, 23.1) Pre-eclampsia 2.7 (1.3, 5.4) 2.7 (1.3, 5.6) Chorioamnionitis 3.3 (1.1, 10.2) 3.3 (1.0, 10.0) Table III. Clinical manifestations of placental abruption n

/198

Characteristic

• No. (%)

Placental abruption detected During labor 52 (26) Before labor 146 (74) Vaginal bleeding 138 (70) Abdominal pain, uterine tenderness, uterine tetanic contractions, or hypertonic uterus 100 (51) Bloody amniotic fluid 93 (50) Fetal heart rate abnormalities 137 (69) Retroplacental blood clot by ultrasound 30 (15) Decreased fetal movements 22 (11) Onset of symptoms before delivery B

/1 h

47 (24) 124 h 108 (55)

• /24 h

22 (11) Unknown 21 (11) Extent of abruption Total 13 (7) Partial 185 (93)

702

• M. Tikkanen et al.

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adds to our earlier study of sociodemographic and historic risk factors for placental abruption (8). The strength of our study was systematic data collection and a relatively large sample size. Our case series were collected at the time when screening and diagnostic ultrasound examinations were extensively used in obstetrical practice. This allowed us to evaluate whether the liberal use of ultrasound had any obvious impact on the diagnosis or management

• f placental abruption, although our study was not a

randomized trial. Smoking is a well known risk factor for placental abruption (9). In our series maternal smoking during pregnancy doubled the risk of placental abruption, and so did paternal smoking. This is in line with a meta-analysis showing that smoking increases the risk of placental abruption by 90% (9). We found that the risk was nearly five-fold if both parents

• smoked. The mechanisms explaining the association

between smoking and placental abruption remain largely speculative, but may include decidual necro- sis at the margin of the placenta, placental micro- infarcts, atheromatous or fibrinoid changes, and the presence of hypovascular and atrophic placental villi (10). Most of these changes reduce the blood flow in the uteroplacentalfetal unit or cause alteration in the endothelial production of prostacyclin and may increase the risk for abruption (10). During the study period, approximately 15% of pregnant wo- men in Finland were smokers (11). It has been postulated that women who stop smoking early in pregnancy have similar risk of abruption to women who have never smoked (10). We point out that pregnant women should be strongly advised to stop smoking during pregnancy; however, this succeeded

• nly in 11% of all smoking women in our study. In

another study, smoking discontinuation rate was 18% (12). Our series was too small to evaluate whether stopping smoking reduces the rate of placental abruption, but previous data imply that 1525% of placental abruptions could be prevented if women stopped smoking during the preg- nancy (9). Thus, up to 50 cases in our series could have been prevented. Clearly, placental abruption must be added to the other risks associated with smoking (10). An intriguing question is why paternal smoking has such a strong independent association with placental abruption irrespective of whether or not the woman smokes. It could simply be explained by passive exposure of the pregnant woman to the partner’s smoking. Another explanation could be that women whose partners smoke also smoke themselves despite claiming being nonsmokers. A Finnish study based on cotinine assessment suggests that about one quarter of smoking parturients deny this habit (13). Smoking by both partners may indicate a more liberal attitude towards smoking in

• general. Thus, it is possible that the partner’s

smoking

• nly

reflects the impact

• f

maternal smoking. Alcohol use during pregnancy is a known risk factor for fetal neurodevelopmental abnormalities and several fetal malformations (14,15). It can also restrict fetal growth and cause stillbirth. No level of alcohol consumption during pregnancy has been determined safe. In Finland, 35% of pregnant women use 10 or more weekly doses of alcohol during pregnancy and hence can be considered heavy users. Our result is in contrast to some previous data (16), but in line with older French (15) or Finnish studies (17). Alcohol easily crosses placenta and disturbs the hormonal balance in the mother and fetus (18), possibly contributing to the risk for abruption. Bleeding during the second or third trimesters, placenta previa, pre-eclampsia, and chorioamnionitis also were risk factors for placental abruption. This is in accordance with previous studies (2,16). The presence of a retroplacental hematoma in the first trimester is known to increase the risk for subse- quent placental abruption (19,20). Vaginal bleeding after 28 weeks also predicted placental abruption in

• ur study, as has been shown before (1). However,

bleeding in the second or third trimesters were not independent risk factor in the adjusted analyses, which can be explained by the dominant impact of placenta previa on placental abruption. We found that pre-eclampsia was associated with a 2.7-fold risk of placental abruption, while chronic hypertension or PIH was not. Our data are in line with previous findings (16). Eclampsia is strongly Both pain and bleeding 38 % Bleeding without pain 31 % Pain without bleeding 12 % No pain nor bleeding 19 %

Figure 1. Pain and vaginal bleeding as symptoms of placental abruption.

Clinical presentation and risk factors of placental abruption 703

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associated with abruption (21). However, none of

• ur patients developed eclampsia.

PPROM has been associated with the risk of placental abruption (21,22), which may be a con- sequence of ascending intrauterine infection. An-

• ther

study showed that prolonged PPROM increased the risk of abruption even more (23). However, this was not seen in our study and may be due to the liberal use of prophylactic antibiotics, which may prevent chorioamnionitis to some extent,

• r due to the fact that we induce labor within 1224

h after PPROM if the duration of gestation exceeds 34 weeks. These policies may explain our result, but controlled prospective trials are needed in order to test this hypothesis. Nevertheless, chorioamnionitis was associated with placental abruption also in our series. Assisted conception, polyhydramnion, oligohy- dramnion, maternal diabetes, uterine trauma, ex- ternal cephalic version, short umbilical cord, velamentous insertion, coagulation defects, amnio- centesis, and placental biopsy have all been asso- ciated with placental abruption in some cases. None

• f these risk factors was associated with placental

abruption in our study. Our cases were not system- atically tested for thrombophilic disorders. More-

• ver, in some (24,25), but not all studies (16),

multiple pregnancy has been a risk factor for placental abruption. This was not seen in our study. Many of these claimed risk factors were infrequent, and can only be addressed in large epidemiological studies. More than 90% of our cases with abruption were delivered by cesarean section. This rate is much higher than in most previous studies (22,26), and may be in part due to the routine use of ultrasound

• examination. The rate of cesarean section among

controls was also high (24%) because our unit serves as the tertiary center for high-risk pregnancies. The

• verall rate of cesarean section in Finland is approxi-

mately 16% (11). According to the literature, up to 50% of abrup- tions take place during labor (1), but this was the case in only 27% of our patients. Once again, the liberal use of ultrasound examination and cesarean section at an early phase in patients suspected of having abruption may have contributed to this

• difference. The clinical manifestations of placental

abruption can be highly variable. Vaginal bleeding was the most common symptom (70%) of placental abruption, and pain was present in half of the cases. Clear retroplacental blood clot before delivery was detected by ultrasound in only 15% of our cases. However, it is remarkable that one out of five cases had neither pain nor bleeding. This highlights the need for close surveillance, particularly among women with established risk factors for placental

• abruption. This may include a lower threshold for

hospitalization or more frequent visits to the mater- nity outpatient clinic. Prematurity and IUGR are major problems associated with placental abruption (27); 59% of the case women had a preterm birth and 25% of the newborns were growth restricted. Also, perinatal mortality was increased 9-fold. In conclusion, maternal smoking and alcohol consumption, and paternal smoking predispose wo- men to placental abruption. These risks can be reduced and ultimately eliminated by health educa- tion and counseling. Placental abruption presents mainly with bleeding and pain but these traditional symptoms were absent in one out of five cases. The liberal use of ultrasound contributed little to the management of women with placental abruption. Acknowledgements This study was supported by the Helsinki University Hospital Research Grants. References

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