Determinants of Maternal and Neonatal Outcomes of Oligohydramnios After 37+0 Weeks of Gestation in Mekelle Public Hospitals, Northern Ethiopia

Background Oligohydramnios is a state of decient amniotic uid dened objectively using ultrasound measurements as single deepest vertical pocket less than 2 centimeters and/or amniotic uid index less than 5 centimeters. It has been correlated with conditions that threaten both maternal and fetal health. The aim of this stuy is to assess determinants of adverse maternal and perinatal outcome in women with oligohydramnios after 37 +0 weeks in Ayder Comprehensive Specialized Hospital and Mekelle General Hospital from April 1, 2018 – March 31, 2019. Methods This was prospective observational study. Total population purposive sampling method was employed to collect data prospectively. Result During the study period, there were a total of 10,451 deliveries, of which 273 were complicated with oligohydramnios, making the prevalence of term oligohydramnios 2.6%. The composite adverse perinatal and maternal outcomes were 38.1% and 89.4% respectively. Primigravidity, degree of oligohydramnios, presence of intrauterine growth restriction and postterm pregnancy were associated with adverse perinatal outcome. Degree of oligohydramnios and hypertensive disorders of pregnancy were found to be predictor of composite adverse maternal outcome. Conclusion Appreciation of determinants of composite adverse maternal and neonatal outcome can aid prompt interventions and mobilization of resources for resuscitation and early transfer to neonatal intensive care unit. Knowledge of determinants of maternal outcome can serve as a tool for patient counseling and for anticipation of maternal complications. This study concludes that women with oligohydramnios after 37 + 0 weeks gestation experience signicantly increased morbidities in terms of composite adverse perinatal and maternal outcome. This study helps to delineate presence of which factors determine a composite adverse perinatal and maternal outcome. It can be concluded that presence of IUGR, being primigravid, degree of oligohydramnios, presence of hypertensive disorders of pregnancy and post term gestation are predictors of experiencing composite adverse perinatal outcome in women with oligohydramnios after 37 + 0 weeks of gestation. Degree of oligohydramnios and HIV serostatus are signicant independent predictors of composite adverse maternal outcome.


Introduction
Oligohydramnios is a state of de cient amniotic uid de ned sonographycally as single deepest vertical pocket less than 2 centimeters and/or amniotic uid index less than 5 centimeters [1]. Studies from different institutions and countries show that the prevalence of oligohydramnios ranges from 1-5% at term but it can go as high as 12-14 % after 41 weeks and as high as 30% in postterm pregnancies [1][2][3][4][5][6].
The reported prevalence of oligohydramnios at term gestation in the Ethiopian context is 2.3% [7].
Oligohydramnios has always been a topical issue in obstetrics because it is associated with grave perinatal outcome and increased maternal operative interventions. It is associated with adverse perinatal outcomes of poor rst minute APGARs, increased risks of thick meconium in labor and risks of meconium aspiration, high admission rates to neonatal intensive care unit (N-ICU) and risks of perinatal deaths. There is an association of oligohydramnios with intrauterine growth restriction (IUGR) and risks of congenital anomalies in the babies.
This condition also puts the mother at risks of procedures and operative interventions of induction and cesarean delivery [3,4,8,9]. Mothers with oligohydramnios are at increased risk of delivering via cesarean section primarily due to abnormal fetal wellbeing in labor [2,10 -12]. Studies show high rate of cesarean delivery in both high -income and low -income countries ranging from 42.0 -83.6% [2-4,7,8,13 -15].
To the contrary there are studies that show oligohydramnios does not predict maternal and neonatal outcome. According to this studies there is a need for increased pregnancy surveilance if an oligohydramnios is detected. Otherwise, pregnancy interventions including induction or cesarean delivery for the mere presence of oligohydramnios cannot be justi ed [6,9,16]. In general there is no su cient evidence to optimize the management of women with oligohydramnios and hence has always been area of controversy.
At Ayder Comprehensive Specialized and Mekelle General Hospitals, there is no continuous fetal monitoring with tracing. Therefore, owing to the perceived uncertainity of the intrapartum follow up and the increased rate of cesarean delivery in labor in those who are induced, there is a trend to lower a threshold to do elective cesarean delivery in cases of oligohydramnios.
There is an observed high prevalence of oligohydramnios and associated maternal and fetal morbidities in our set -up. Yet, no study examined maternal and fetal complications and outcomes associated with oligohydramnios in Mekelle General and Ayder Comprehensive Specialized Hospitals. Only few studies have been conducted on the subject in the Ethiopian context. With this in mind, this study was conducted to see the prevalence of oligohydramnios and examine determinant predictors of composite adverse maternal and neonatal outcomes.
Oligohydramnios poses a dilemma in management specially in set -ups with no continuous fetal monitoring [6]. Due to intrapartum complication and high rate of perinatal morbidity and mortality associated with oligohydramnios, rates of caesarean section are rising, but decision between vaginal delivery and caesarean section should be well balanced so that unnecessary maternal morbidity is prevented and perinatal morbidity and mortality are reduced [6,13].
Context speci c appreciation of magnitude of the problem of oligohydramnios and factors related to poor outcome could help stratify management of these mothers and can aid prompt interventions and mobilization of resources for resuscitation and early transfer to NICU. It can also serve as a baseline local data against which mothers and their family could be advised and counseled about the degree of perinatal morbidity and mortality this condition incurs.

Biological importance of Oligohydramnios
Amniotic uid serves to protect the fetus and umbilical cord from compression. It also has antibacterial properties, serves as a reservoir of water and nutrients and provides the necessary condition for normal development of fetal lung, musculoskeletal and gastrointestinal system, regulates temperature, reduces the impact of uterine contractions on the fetus [8,13]. It enables continued fetal growth in a nonrestricted, sterile and thermally controlled environment [17].
Excessive or de cient amniotic uid volume [AFV] has been used to indicate pregnancies that may be at risk for poor outcome. Such pregnancies have been associated with an increased anomaly rate, as well as increased perinatal morbidity and mortality [18]. Decreased amniotic uid volume is especially of concern when it occurs in conjunction with structural fetal anomalies, fetal growth restriction, postdates pregnancies, and maternal disease [19,20].
Methods of determining amniotic uid volume Different tests have been proposed to determine amniotic uid volume as mean of evaluation of fetal wellbeing [12]. Amniotic uid index [AFI] and single deepest pocket [SDP] are the most-used semiquantitative techniques. AFI is calculated by summing the depth in centimeters of 4 different pockets of uid not containing cord or fetal extremities in 4 abdominal quadrants using the umbilicus as a reference point and with the transducer perpendicular to the oor [4,21,22]. SDP refers to the vertical dimension of the largest pocket of amniotic uid [with a horizontal measure of at least 1 cm not containing umbilical cord or fetal extremities and measured at a right angle to the uterine contour and perpendicular to the oor. SDP is the criterion used in the biophysical pro le to document adequacy of AFV [18,21].
AFI and SDVP have been validated as an accurate and reproducible techniques for assessment of amniotic uid volume and are associated with poor perinatal outcome and increased maternal morbidities [9]. Howevere the AFI identi es a signi cantly greater number of women as having oligohydramnios versus the SDP but without any difference in perinatal outcomes. Compared with SDP, AFI excessively characterizes a greater number of pregnancies as having oligohydramnios leading to more interventions without improvement in perinatal outcome [23].

Complications of Oligohydramnios Adverse Perinatal Outcome
Oligohydramnios is one of the severe obstetric complications with poor fetal and maternal outcome. It is associated with low Apgar scores and NICU admissions, even in the absence of other 'high-risk' characteristics [14]. Risk of meconium stained liquor can go as high as 40-44%, respiratory distress as high as 13%, NICU admission as high as 15-19%, perinatal death 2.4 -6.4 % and the composite adverse perinatal outcome can go as high as 15% [7]. Rates of fetal distress in labor can go as high as 30% and as high as 20% of neonates are reported to have low rst minute Apgar [24].
Generally the risk of adverse perinatal outcome is increased in oligohydramnios including both gross and corrected perinatal mortality [25]. In one study in 7587 high risk patients Gross and corrected perinatal mortality in association with normal qualitative amniotic uid volume ranged from 4.65/1000 and 1.97/1000, respectively, to 187.5/1000 and 109.4/1000 in association with decreased qualitative amniotic uid volume, respectively [25].
In postterm pregnancies, ppatients with reduced amniotic uid had a signi cant increase in meconiumstained amniotic uid and growth-retarded babies and were more likely to require delivery by caesarean section for fetal distress and ultrasound measurement of amniotic uid represents an effective discriminatory test in post-term pregnancy [26]. More important, adverse perinatal outcome is signi cantly more frequent with severely diminished compared with borderline amniotic uid volume [4,27].

Risk Factors for Oligohydramnios
Majority of cases of oligohydramnios are idiopathic. The commenst and persistent maternal causes and risk factors of oligohydramnios are hypertension, anemia, premature rupture of the membrane (PROM), postdate and postterm pregnancy and abruption [2,8,14]. Chronic abruption can lead to a condition called chronic-abruption-oligohydramnios sequence (CAOS) in early pregnancy [31]. There are also case reports of malaria as a cause of oligohydramnios [32].
There are also mirads of fetal congenital anomalies that cause oligohydramnios. The commenest are congenital anomaly of the kidneys and urinary tracts (CAKUT), potter syndrome, and amniotic band syndrome [11,14]. Therefore, a thorough fetal anatomic survey focusing on the genitourinary tract and an attempt at visualizing free amniotic bands should be performed with ultrasound inn cases of oligohydramnios [33]. Management of oligohydramnios also warrants increased antepartum surveillance for early detection of pregnancy complications and fetal scanning growth restriction [34]. Midtrimester oligohydramnios can also lead to the development of fetal pulmonary hypoplasia [35].
Therefore the delivery should be conducted under circumstances that allow appropriate support and intervention on behalf of the fetus [34] and vaginal delivery necessiates continuous intrapartum fetal heart rate monitoring [11].

Research Methods And Materials
Study Setting The study was conducted at Ayder Comprehensive Specialized and Mekelle General Hospitals. Both are public hospitals with speciality services.
Ayder Comprehensive Specialized Hospital is one of the largest public hospitals in Ethiopia serving as a referral catchment area for more than 8 million people from Tigray, Afar, and Northern Amhara Regional States. It is tertiary hospital giving all types of care. It provides a comprehensive care of which obstetrics and gynecology care service provision is one of the main services. It has two separate Out Patient Departments; one offering services for low risk mothers and the other for high risk mothers. There are 78 in -patient beds in two wards, 4 delivery couches, 1 emergency room, 2 procedure rooms and 1 meeting hall for Obstetrics and Gynecology care services. There is also an OR table reserved only for emergency cesarean delivery in the main OR. During the study period, there were 10 senior Obstetrician and Gynecologists, 34 residents, 40 midwives and 27 nurses providing the care. This hospital hosted 5,163 deliveries during the study period.
In terms of outpatient obstetric services, it has two out -patient clinics in two separte buildings. There is an out -patient clinic separate from the main hospital building but in the same premises, where women are primarily triaged during their rst st. Those who are low risk continues follow up at the low risk clinic. Women who are high risk at the rst triage or women who are subsequently diagnosed or develop high risk condtion on subsequent contacts are send to the high risk clinic located in the center of the main building. Those who are high risk are followed separately in a high risk clinic.

Mekelle General Hospital is an a late hospital of Ayder Comprehensive Specialized Hospital where
Residents and Seniors from ACSH rotate monthly to deliver Obstetric and Gynecology services. It smiliarly hosted 5,155 deliveries during the study period.

Study Design
This was prospective observational study.

Source population
All pregnant women who seek service at Mekelle town public hospitals.

Study population
All pregnant women who were diagnosed to have oligohydramnios by ultrasound and getting service at Mekelle Hospital and Ayder Comprehensive Specialized Hospital during the study period.

Study Subjects
All pregnant women who full lled the inclusion criteria are enrolled in the study .  [36]. Statistical power is 80 and two sided signi cance level is 95% giving sample size of 135.  Concerning the presence of possible cause of oligohydramnios, no plausible cause of oligohydramnios was present in nearly half of the cases. Prolonged pregnancy, hypertensive disorders of pregnancy and severe IUGR were the most common problems identi ed accounting for 37.4%, 7.3% and 6.2% respectively. More than half of the cases had AFI < 2 [    Table 4].  Table 6].  Table 6].   Odds of experiencing composite adverse maternal outcome nearly doubles, triples and quadraples in women with hypertensive disorders of pregnancy compored to those whithout, oligohydramnios at early term gestation compared to those at full term and in those who are not married compared with those who are married respecrtively but these variables did not show an actual signi cant stastistical trend [ Table   8].  [7]. However, the present study did not nd an association in between mode of delivery and composite adverse perinatal outcome.
Perinatal adverse outcome in women who present at 42 + 0 weeks or beyound is twice -seven times higher than that of pregnancies who present at full term [39]. The thirteen times increased risk observed in the present study cannot be explained by only being post term. Thus, post term can be taken as an independent predictor of adverse perinatal outcome in women who present with oligohydramnios. Similary, IUGR is a marker of adverse outcome by itself [40,41]. The signi cantly higher rates of composite adverse perinatal outcome in the present study reveals IUGR as a signi cant independent predictor of adverse outcome in women with oligohydramnios.

Conclusion
This study concludes that women with oligohydramnios after 37 + 0 weeks gestation experience signi cantly increased morbidities in terms of composite adverse perinatal and maternal outcome. Hospital director's o ce to undertake the study before start of data collection. Written informed consent was obtained from all mothers who participated in this study. The data was not used for other purpose other than the objective of the study. Names and other identi ers were not used in collecting the data, and con dentiality was maintained by keeping the data collection forms locked in a cabinet and the electronic data les were kept in password protected computer.

Consent for Publication
Not applicable Availability of data and materials The datasets used and/or analyzed during the present study can be accessed from the corresponding author up on reasonable request. Diagram showing how the two hospitals were chosen for the study

Supplementary Files
This is a list of supplementary les associated with this preprint. Click to download. FinalFormofOligohydramniosDataExtractionForm.pdf