This document summarizes various types of abnormal uterine action that can occur during labor and delivery. It describes normal labor progression and defines abnormalities as any deviation from the normal pattern of uterine contractions that affects the course of labor. Various types of abnormalities are outlined, including dysfunctional labor, uterine inertia, incoordinate uterine action, cervical dystocia, and precipitate labor. Causes, diagnostic features, effects on the mother and fetus, and management approaches are provided for each abnormality.

1. Abnormal Uterine Action
Under the guidance of: Dr Arshiya Sultana
By: Rashida Sadath

2. • Normal labor  coordinated uterine contractions  progressive
dilatation of the cervix  descent of the fetal head.
• Cervical dilatation
Nulliparous ≥ 1 cm/hr.
Multiparous ≥ 1.5 cm/hr.
• Labor abnormalities
25% nulliparous women
10% multiparous women.

3. Abnormal active phase
1. Protraction disorder
Inadequate or abnormal
uterine contractions
2. Abnormal uterine action
Any deviation of the normal
pattern of uterine
contractions affecting the
course of labor

5. ETIOLOGY:
Remains obscure.
However, the following clinical conditions are often associated:
(1) Prevalent in first birth, especially with elderly women
(2) Prolonged pregnancy
(3) Overdistension of the uterus (twins and fibroids)
(4) Emotional factor (anxiety, stress)
(5) Constitutional factor (obesity)
(6) Contracted pelvis and malpresentation
(7) Injudicious administration of sedatives, analgesics and oxytocics
(8) Premature attempt at vaginal delivery (induction of labor or ARM) or
attempted instrumental vaginal delivery under light anesthesia.

6. The uterine pacemaker is situated at the cornua of the uterus and this
generates uterine contractions.
Starts at cornua  gradually sweeps downwards.
Primary dysfunctional labor  uterine activity instead of being
governed by a single dominant pacemaker, is shifted to less efficient
contractions due to emergence of other pacemaker foci.
Oxytocin therapy may be effective in restoring
the global and effective uterine contractions.

7. Primary dysfunctional labor
• When the cervix dilates < 1 cm/hr following a normal latent phase of
labor.
• Most common abnormality. Corrected by amniotomy and/or oxytocin
augmentation.
Secondary arrest
• When the cervical dilatation stops after the active phase of labor has
started normally.
• Secondary arrest of dilatation may be due to (a) Poor uterine
contractions (myometrial fatigue), (b) Cessation of cervical dilatation
despite strong uterine contractions (disproportion, malpresentation)

8. Uterine activity (contraction) is measured by noting
(i) basal tone
(ii) active (peak) pressure
(iii) frequency
Assessment is usually done by:
(i) Clinical palpation—(inaccurate)
(ii) Tocodynamometer with external transducer
(iii) Intrauterine pressure catheter (IUPC) is used to measure intrauterine
pressure during uterine contractions

9. • Normal baseline tonus is between 5 mm Hg and 20 mm Hg.
• Minimum uterine pressure required to dilate the cervix is 15 mm Hg
over the baseline.
• Normal uterine contractions in labor create an intrauterine pressure up
to 60 mm Hg.
• Oxytocin is to be used when uterine contractions are inadequate.
• Oxytocin dose is to be escalated till the optimum uterine contractions
(3–4 per 10 minutes) with a peak intrauterine pressure of 50–60 mm Hg
and a resting tone of 10–15 mm Hg is obtained.

10. UTERINE INERTIA
(HYPOTONIC UTERINE DYSFUNCTION)
Uterine inertia is the common type of abnormal uterine contraction but
is comparatively less serious.
It may complicate any stage of labor.
It may be present from the beginning of labor or may develop
subsequently after a variable period of effective contractions.

11. UTERINE CONTRACTION:
The intensity is diminished; duration is shortened; good relaxation in
between contractions and the intervals are increased.
General pattern of uterine contractions of labor is maintained but
intrauterine pressure during contraction is less than 25 mm Hg.

12. DIAGNOSIS:
(1) Patient feels less pain during uterine contraction
(2) Hand placed over the uterus during uterine contraction reveals less
hardening of the uterus
(3) Uterine wall is easily indentable at the acme of a pain
(4) Uterus becomes relaxed after the contraction, fetal parts are well
palpable and fetal heart rate remains normal
(5) Internal examination reveals—(a) Poor dilatation of the cervix
(normal rate of dilatation in primigravida should be at the rate of 1
cm/hr beyond 4 cm dilatation); (b) Presence of cephalopelvic
disproportion, malposition, deflexed head or malpresentation
may be evident; (c) Membranes intact.

14. EFFECTS ON THE MOTHER AND FETUS:
Maternal exhaustion and/or fetal distress are unusual and appear late.

15. MANAGEMENT:
Case is reassessed to exclude cephalopelvic disproportion or
malpresentation.
Need for cesarean section:
(1) Presence of contracted pelvis
(2) Malpresentation
(3) Evidences of fetal or maternal distress.

16. Vaginal delivery
(A)General measures: (1) To keep up the morale of the patient.
Maternal stress, pain and anxiety appear to inhibit uterine contractions
through release of endogenous catecholamines. (2) Posture of the
woman is changed. Supine position is avoided. (3) To empty the
bladder, catheterization is made. (4) To maintain hydration by
infusion of Ringer’s solution. (5) Adequate pain relief.
(B) Active measures: Acceleration of uterine contraction can be brought
about by low rupture of the membranes followed by oxytocin drip.
The drip rate is gradually increased until effective contractions are
set up. The drip is to be continued till 1 hour after delivery

17. INCOORDINATE UTERINE ACTION
It usually appears in active stage of labor.
The hypertonic state of the uterus arises from any of the conditions
such as
• spastic lower uterine segment
• colicky uterus
• asymmetrical uterine contraction
• constriction ring or generalized tonic contraction of the uterus
and all these states are collectively called incoordinate uterine action.

18. • Increased frequency and/or duration of uterine contractions  rise in
baseline tone  diminish circulation in the placental intervillous space
 fail to make progressive cervical effacement and dilatation.
• Frequent contraction of low amplitude causes elevation of basal
intrauterine pressure.
• There is often maternal discomfort.
• Aminotomy with or without oxytocin augmentation is usually done
when the women in the active phase of labor.
• Conservative management is done if it occurs in the latent phase.
• Uterine tonus is elevated.

19. • Pain is present before, during and after contractions  fetal hypoxia in
labor.
• Placental abruption is often associated with high baseline tone (> 25 mm
Hg).
• On CTG the FHR shows reduced variability and late decelerations.
• Uterine hyperstimulation due to oxytocics (oxytocin, prostaglandins)
are often associated with fetal tachycardia (fetal adrenergic activity) due
to fetal stress.

20. SPASTIC LOWER SEGMENT — UTERINE CONTRACTION:
(1) Fundal dominance is lacking and often there is reversed polarity.
(2) The pacemakers do not work in rhythm
(3) The lower segment contractions are stronger
(4) Inadequate relaxation in between contractions
(5) Basal tone is raised above the critical level of 20 mm Hg

21. Diagnosis:
(1) The patient is in agony with unbearable pain referred to the back. There
are evidences of dehydration and ketoacidosis
(2) Bladder is frequently distended and often there is retention of urine;
distension of the stomach and bowels are visible
(3) There are premature attempts to bear down
(4) Abdominal palpation reveals: (a) Uterus is tender and gentle manipulation
excites hardening of the uterus with pain, (b) palpation of the fetal parts is
difficult
(5) Fetal distress appears early
(6) Internal examination may reveal: (a) Cervix which is thick, edematous hangs
loosely like a curtain; not well applied to the presenting part, (b)
Inappropriate dilatation of the cervix, (c) Absence of the membranes, (d)
Meconium stained liquor amnii may be there.

22. Effect on the fetus:
Fetal distress appears early due to placental insufficiency caused by
inadequate relaxation of the uterus.
Management:
• There is no place of oxytocin augmentation with this abnormality.
• Cesarean section is done in majority of cases.
• Prior correction of dehydration and ketoacidosis must be achieved by
rapid infusion of Ringer’s solution

23. CONSTRICTION RING (Syn: Contraction ring, Schroeder’s ring):
It is one form of incoordinate uterine action where there is localized
myometrial contraction forming a ring of circular muscle fibers of the
uterus.
It is usually situated at the junction of the upper and lower segment
around a constricted part of the fetus usually around the neck in cephalic
presentation.
It may appear in all the stages of labor.
It is usually reversible and complete.

25. The common causes are: (1) injudicious administration of oxytocics, (2)
premature rupture of the membranes, and (3) premature attempt at
instrumental delivery.
Diagnosis: Diagnosis is difficult.
• It is revealed during cesarean section in the first stage, during forceps
application in the second stage and during manual removal in the third
stage (hour-glass contraction).
• The ring is not felt per abdomen. Maternal condition is not much
affected but the fetus is in jeopardy because of the hypertonic state.
• Uterus never ruptures.

26. Treatment:
• Delivery is usually done by cesarean section.
• The ring usually passes off by deepening the plane of anesthesia
otherwise the ring may have to be cut vertically to deliver the baby.
• The difficulties faced during forceps delivery (second stage) or during
normal removal of placenta (third stage) can be overcome by using deep
anesthesia that relaxes the constriction ring.

27. CERVICAL DYSTOCIA:
Progressive cervical dilatation needs an effective stretching force by the
presenting part.
Failure of cervical dilatation may be due to
(a) Inefficient uterine contractions
(b) Malpresentation, malposition (abnormal relationship between the
cervix and the presenting part)
(c) Spasm (contractions) of the cervix.
Cervical dystocia may be primary or secondary

28. Primary:
Commonly observed during the
(i) First birth where the external os fails to dilate
(ii) Rigid cervix
(iii) Inefficient uterine contractions and the others (as mentioned earlier).
Treatment:
• In presence of associated complications (malpresentation, malposition),
cesarean section is preferred.
• If the head is sufficiently low down with only thin rim of cervix left behind,
the rim may be pushed up manually during contraction or traction is given by
ventouse.
• In others, where the cervix is very much thinned out but only half dilated.
Dührssen’s incision at 2 and 10’O clock positions followed by forceps or
ventouse extraction is quite safe and effective.

29. SECONDARY CERVICAL DYSTOCIA:
This type of cervical dystocia results usually due to excess scarring or
rigidity of the cervix from the effect of previous operation or disease.
Others are:
(i) Post-delivery
(ii) Postoperative scarring
(iii) Cervical cancer.

30. • GENERALIZED TONIC CONTRACTION (Syn: Uterine tetany):
• In this condition, pronounced retraction occurs involving whole of the
uterus up to the level of internal os.
• Thus, there is no physiological differentiation of the active upper
segment and the passive lower segment of the uterus.
• The whole uterus undergoes a sort of tonic muscular spasm holding
the fetus inside (active retention of the fetus).
• Usually there is no risk of rupture uterus. New pacemakers appear all
over the uterus.

31. Causes:
(i) Cephalopelvic disproportion
(ii) Obstruction
(iii) Injudicious use of oxytocics

33. Clinical features:
• The patient is in prolonged labor having severe and continuous pain.
• Abdominal examination reveals the uterus to be somewhat smaller in size,
tense and tender.
• Fetal parts are neither well defined, nor is the fetal heart sound audible.
• Vaginal examination reveals jammed head with big caput, dry and
edematous vagina.
Treatment: •
• Correction of dehydration and ketoacidosis—by rapid infusion of Ringer’s
solution •
• Antibiotic—to control infection •
• Adequate pain relief

34. Hypercontractility (tachysystole)
• May be induced by oxytocics (>5 contractions in 10 min).
• It may occur in spontaneous or with stimulated labor.
• Persistent tachysystole with FHR abnormality can cause fetal hypoxia.
• It can be managed by tocolytics (Terbutaline 0.25 mg SC).
• Oxytocin infusion should be stopped.
• Cesarean delivery is done in majority of the cases, especially when
obstruction is suspected.

35. PRECIPITATE LABOR
• A labor is called precipitate  duration of the first + second stage = <3
hours.
• Prevalence is 2%.
• Short labors may be associated with:
1. Placental abruption
2. Uterine tachysystole

36. • It is common in multiparae and may be repetitive.
• Hyperactive uterine contractions + diminished soft tissue
resistance = Rapid expulsion
• Nulliparous women = cervical dilatation > 5 cm/hr or more

37. Maternal risks:
(1) Extensive laceration of the cervix, vagina and perineum (to the
extent of complete perineal tear)
(2) PPH due to uterine hypotonia that develops subsequent to unusual
vigorous contractions
(3) Inversion
(4) Uterine rupture
(5) Infection
(6) Amniotic fluid embolism.

38. Fetal risks:
1. Intracranial stress and hemorrhage because of rapid expulsion
without time for molding of the head.
2. The baby may sustain serious injuries if delivery occurs in standing
position.
3. Bleeding from the torn cord and direct hit on the skull, brachial
plexus injury are real hazards.

39. Treatment:
• The patient having previous history of precipitate labor should be
hospitalized prior to labor.
• During labor, the uterine contraction may be suppressed by
administering ether or magnesium sulfate during contractions.
• Delivery of the head should be controlled.
• Episiotomy should be done liberally.
• Elective induction of labor by low rupture of membranes and
conduction of controlled delivery is helpful.
• Oxytocin augmentation should be avoided.

40. TONIC UTERINE CONTRACTION AND RETRACTION (Syn: Bandl’s ring,
Pathological retraction ring
This type of uterine contraction is predominantly due to obstructed labor.
Pathological anatomy of the uterus:
• There is gradual increase in intensity, duration and frequency of uterine
contraction.
• The relaxation phase becomes less and less; ultimately a state of tonic
contraction develops.
• Retraction, however, continues.

41. • The lower segment elongates and becomes progressively thinner to
accommodate the fetus driven from the upper segment.
• A circular groove encircling the uterus is formed between the active
upper segment and the distended lower segment, called pathological
retraction ring (Bandl’s ring).
• Due to pronounced retraction, there is fetal jeopardy or even death.
• In primigravidae, further retraction ceases in response to obstruction and
labor comes to a stand still—a state of uterine exhaustion.
• Contractions may recommence after a brief period of rest with
renewed vigor.

42. • But in multiparae, retraction continues with progressive circumferential
dilatation and thinning of the lower segment.
• There is progressive rise of the Bandl’s ring, moving nearer and
nearer to the umbilicus and ultimately, the lower segment ruptures.

43. Clinical features:
(1) Patient is in agony from continuous pain and discomfort and becomes
restless.
(2) Features of exhaustion and ketoacidosis are evident.
(3) Abdominal palpation reveals:
(a) Upper segment is hard and tender.
(b) Lower segment is distended and tender.

44. Management:
• Prevention—Partographic management of labor.
• Early diagnosis of malpresentation.
• Disproportion and delivery by cesarean section can prevent this
condition completely.

45. Treatment: „
• Rupture of uterus is to be excluded „
• Internal version is contraindicated „
• Correction of dehydration and ketoacidosis by infusion of Ringer’s
solution „
• Adequate pain relief
• „Parenteral antibiotic is given (Ceftriaxone 1 g IV) „
• Cesarean delivery is done in majority of the cases.
• Rupture of uterus must be excluded before attempting destructive
operation

50. SUMMARY
• Abnormal Uterine Action is due to development of abnormal polarity on the
uterus.
• It may manifest as uterine inertia (common) or hypertonic dysfunction due to
any mechanical factor (obstruction).
• Hypertonic dysfunction may end in either formation of Bandl’s ring or
precipitate labor.
• Incoordinate uterine action (asymmetric uterine contractions, constriction ring
and cervical dystocia) can affect the health of both the mother and the fetus
adversely.
• It is important to detect AUA early and to institute management appropriately
to reduce maternal and neonatal morbidity and mortality.

51. Preventive Measures of Dystocia due to Abnormal Uterine Action:
(1) Quality antenatal care, emotional support to be parturient and close
monitoring of labor can reduce abnormal uterine action.
(2) Induction of labor should be judicious, especially when the cervix is
unfavorable.
(3) Amniotomy in the latent phase or as a routine procedure is to be
avoided.
(4) During the course of labor the woman should be given adequate moral
support, rest and analgesic. Her hydration should be maintained.
(5) Management of labor should be plotted partographically so that any
deviation from the normal is detected and managed early.