Induction of Labor. Amr Nadim, MD Professor of Obstetrics & Gynecology Ain Shams Faculty of Medicine [[email protected]]. Nice to Know. Likely to know. Should Know. Core. What you MUST know about this topic. List the different indications for induction of labor.
Likely to know
gestations greater than the legal definition of fetal viability
Induction is indicated when the benefits to either the mother or fetus outweigh those of continuing the pregnancy.
An unfavorable cervix will need RIPENING
1-Relaxation techniques: advise patient to relieve tension and try to relax then use some visual aids to show how labor starts.
2-Visualization: The patient is advised to imagine her uterus contracting and she is laboring. Hypnosis/self-hypnosis helps.
3-Walking: The force of gravity pulls the weight of the baby towards the birth canal leading to dilatation and effacement of the cervix.
4-Sex: Having sex is known to induce labor. This is related to prostaglandin content of the seminal fluid and the occurrence of orgasm which stimulate uterine contractions
5-Nipple stimulation: The lady moves her palm and applies some pressure in a circular fashion over her areola and massaging nipple between thumb and forefingers for a period of 2 minutes alternating with 3 minutes of rest. The procedure is performed for 20 minutes. If adequate contraction pattern is not achieved, massaging was done for 3 minutes alternating with 2 minutes rest for additional 20 minutes. Care should be taken to avoid massaging during a contraction and to only massage one side at a time in order to avoid hyperstimulation.
6-Bath/Castor oil/Enemas:The patient is advised to take a warm bath then to have 3 teaspoons of castoroil mixed with some juice and an enema thereafter.This method could stimulate the uterus to contract, which will cause the cervix to dilate and efface.
7-Foods: Eating lots of pineapple is known to stimulate labor and ripen the cervix. This is possibly related to its enzyme content. Other foods with similar action includePizza, spicy food like Mexican, and tropical fruits
8-Cumin Tea: Used by midwives in Latino cultures. Sugar or honey may be added to lessen its bitter taste
9-Several herbs: Labor-enhancing herbs include blue Cohosh, black Cohosh, Squawvine and Dong Quai. Evening primrose oil also ripens the cervix. It is given internally 5 gel caps up against the cervix daily.
Few health personnel claim an association between some acupressure points in the body and increased uterine contractions. One point is located deep in the webbing between thumb and forefinger. Massaging this point in a circular motion for 1-5 minutes stimulates labor pain and induce labor.
They absorb endocervical and local tissue fluids, causing the device to expand within the endocervix and provide mechanical pressure. These dilators are either natural osmotic dilators (e.g., Laminaria japonicum) or synthetic osmotic dilators (e.g., Lamicel).
Advantages: 1- Outpatient placement 2- No need for fetal monitoring
Risks: fetal and/or maternal infection
Technique of insertion:
-The perineum and vagina are sterilized with betadine & the patient is drapped.
-Using a sterile speculum, the dilator is introduced into the endocervix.
-Dilators are progressively placed until the endocervix is full.
-A sterile gauze pad is placed in the vagina to maintain the position of the dilators.
2- Placement of Balloon Dilators after 42 weeks gestation:
A fluid filled balloon is inserted inside the cervix. The Balloon provide mechanical pressure directly on the cervix which respond by ripening and dilation. A Foley catheter (26 Fr) or specifically designed balloon devices can be used.
Technique of balloon placement:
1- After sterilization and draping, the catheter is introduced into the endocervix either by direct visualization or blindly by sliding it over fingers through the endocervix into the potential space between the amniotic membrane & the lower uterine segment.
2- The balloon is inflated with 30 to 50 mL of normal saline and is retracted so that it rests on the internal os.
3- Constant pressure may be applied over the catheter. e.g. a bag filled with 1 L of fluid may be attached to the catheter end. An intermittent pressure may also be exerted on the catheter end 2 -4 times per hour.
4-Catheter is removed at the time of rupture of membranes or may be expelled spontaneously which indicate a cervical dilatation of 3-4 Centimeter.
1-Stripping the membranes:
Stripping the membranes mechanically dilates the cervix which releases prostaglandins. The membranes are stripped by inserting the examining finger through the internal os & moving it in a circular direction to detach the inferior pole of the membranes from the lower uterine segment.
Risks include patient’s discomfort, infection, bleeding from undiagnosed placenta previa or low lying placenta,and accidental ROM.
The Cochrane reviewers concluded that stripping the membranes, when used as an adjunct, decreases the mean dose of oxytocin needed and increases the rate of normal vaginal deliveries.
( Evidence level A)
2-Amniotomy - Technique:
-The FHR is recorded before the procedure.
-A pelvic examination is performed to evaluate the cervix & station of the presenting part. The presenting part should be well fitted to the cervix.
-The membranes are identified and a kocher is inserted through the cervical os by sliding it along the hand & fingers & membranes are ruptured.
-The nature of the amniotic fluid is recorded (clear, bloody, thick or thin, meconium).
-The FHR is recorded after the procedure.
Risks of amniotomy:
1- Prolapse of the umbilical cord (0.5%)
2- Chorioamnionitis: Risk increases with prolonged induction delivery interval
3- Postpartum hemorrhage: Risk is doubled compared with women with spontaneous onset of labor
4- Rupture of vasa previa
It is inserted vaginally as a gel (Prepidil), as a removable tampon (Cervidil) or as a vaginal pessary.
It acts on the cervical connective tissue and relaxes muscle fibres of the cervix.
Dinoprostone should only be administered at hospital and the patient is expected to stay recumbent and monitored, at least, for the first 30 minutes after insertion.
Contractions usually start within 60 minutes of commencing induction and peak within 4 hours. If optimal response is not achieved by 6 hours, another dose can be administered.
The maximum allowed dose is 3 doses be administered per 24 hours.
Cervidil contains 10 mg of dinoprostone and provides a lower constant release of medication (0.3 mg per hour) than Prepidil does. Cervidil have the advantage of being removed more easily if uterine hyperstimulation occurs. In addition, it does not require refrigeration.
PGE2 can cause uterine hyperstimulation, fetal distress and Cesarean section.
-Misoprostol (Cytotec) is a synthetic PGE1 analog that has been found to be a safe and inexpensive agent for cervical ripening.
Route of administration: Oral, vaginal and sublingual route for induction. Rectal route is used to prevent and treat postpartum hemorrhage.
Bioavailability: Extensively absorbed from the GIT
Metabolism: De-esterified to prostaglandin F analogs
Half life: 20–40 minutes
Excretion: Mainly renal 80%, remainder is fecal: 15%
- Clinical trials indicate that the safe optimal dose and dosing interval is 25 mcg intravaginally every 4-6 hours.
A maximum of 6 doses was suggested.
Higher doses or shorter dosing intervals are associated with a higher incidence of side effects, especially hyperstimulation syndrome.
-Misoprostol should not be used in women with previous CS because of increased rates of uterine rupture (Evidence level B).
- The Cochrane reviewers concluded that use of misoprostol resulted in an overall lower incidence of CS.
- In addition, there appears to be a higher incidence of vaginal delivery within 24 hours of application and a reduced need for oxytocin augmentation. ( Evidence level A).
Mifepristone (Mifeprex) is an antiprogesterone agent which counteracts the inhibitory effect of Progesterone on the uterus.
Few studies with small number of women enrolled, have shown that women treated with mifepristone in a dose of 600 mg are more likely to have a favorable cervix and deliver within 48 to 96 hrs when compared with placebo and also they these were less likely to undergo C.S.
Information about fetal outcomes & maternal side effects is scarse and cannot be used to recommend the use of mifepristone for cervical ripening.
It is given by IV infusion using an automated pump. Oxytocin has many advantages: it is potent and easy to titrate, has a short half-life (one to five minutes) and is well tolerated.
-If infusion volumes were found to be excessive, prepare double strength solution.
-If no progress occurred after 8–12 hours of starting induction, either discontinue the oxytocin and reapply a cervical ripening agent or re-initiate oxytocin the next day.
Side effects of oxytocin use:
1-Uterine hyperstimulation and subsequent FHR abnormalities.
2-Abruptio placentae and uterine rupture.
3-Water intoxication may occur with high concentrations of oxytocin infused with large quantities of hypotonic solutions. Therefore; prolonged administration with doses higher than 40 mu of oxytocin per minute and infusion of fluids in any 10 hours should not excced 1500 ml. A rapid intravenous injection of oxytocin may cause hypotension.
4- Neonatal Hyperbiliribinemia
• uteroplacental insufficiency
• lower metabolic reserves due to intrauterine malnutrition or pre-existing hypoxia
• an umbilical cord more prone to compression due to a reduction in amniotic fluid volume.