Laminaria
Scientific Name(s): Laminaria digitata (L.) Lamour or L. bracteata Ag. ( L. japonica Aresch). Family: Laminariaceae
Common Name(s): Kelp , brown algae , laminaria , horsetail , sea girdles 1
Clinical Overview
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Uses of Laminaria
Laminaria has been used as a hygroscopic cervical dilator and inducer of labor. Other reported activity includes hypotensive and anticoagulant properties and absorption of radioactive strontium. However, an increased risk of infection in neonate and mother as well as potential increase in mortality in the neonate may limit its use.
Laminaria Dosing
Laminaria tents ( Lamicel ) have been used for cervical dilation, therefore no dosing information is required.
Contraindications
Laminaria may cause or contribute to maternal and neonatal infection. Use is contraindicated during pregnancy. Use may be contraindicated in patients taking medications for hyperthyroidism because of the plant's iodine content.
Pregnancy/Lactation
Laminaria may cause or contribute to maternal and neonatal infection. Avoid use.
Laminaria Interactions
None well documented.
Laminaria Adverse Reactions
Laminaria may cause or contribute to maternal and neonatal infection. Patients in clinical studies have reported pain and fever.
Toxicology
The spontaneous uterine contractions that may accompany the use of laminaria have been implicated in the induction of fetal hypoxia and subsequent intrauterine death.
Botany
The marine kelps derived from Laminaria species are found primarily in the cold waters of the North Atlantic and North Pacific oceans.
History
Laminaria for cervical dilation is used in the form of “tents.” A tent is any material, usually hygroscopic (readily absorbs water), which is placed in a canal or chamber to maintain the opening or cause dilation.
Laminaria tents are made from the dried stems of Laminaria seaweeds. When dried and rounded into a stick-like shape, the tent is approximately 6 cm (2.5 inches) long with a diameter of 0.3 to 0.5 cm. A strong thread is attached to one end and a collar prevents its migration into the uterus. The stem is hygroscopic and can swell to 3 to 5 times its original diameter within 12 to 24 hours. Other natural products have been used in the past as tents, including sponges, dried corn stalks, slippery elm bark, and tupelo wood. 2 The use of laminaria became popular in the 1800s; hollow laminaria tents were developed to improve uterine drainage, and laminaria coated with wax was designed to release antiseptics as it melted.
Tents fell into disuse because of complications caused by infections. This was especially evident in tents derived from land plants because of the inability to sterilize Clostridium spores (the causative agents of tetanus, botulism, and gas gangrene). Although laminaria from the ocean contains relatively nonpathogenic bacterial contaminants, polluted waters and poor packaging extended the problems of infections related to its use. However, with the advent of ethylene oxide and gamma irradiation sterilization techniques, interest in laminaria tents returned.
L. bracteata Ag . ( L. japonica Aresch) is commonly used in soup, candy, and sushi, and eaten with rice or as a salad. The plant is harvested as kombu in the Far East and is cultivated in China, Korea, and Japan. 3
Chemistry
Laminarin (laminaran) is a polysaccharide found in Laminaria sap. Soluble and insoluble forms are found in algae. 4 , 5 Kelp (of which Laminaria is one species) are rich in algin, a high molecular weight polysaccharide that forms viscous colloidal solutions or gels in water. This property has led to the use of kelp derivatives as bulk laxatives. 6 The constituents of Laminaria also include iodine, potassium, magnesium, calcium, and iron. 7 , 8 , 9
Laminaria Uses and Pharmacology
Cervical ripeningWhen inserted into the cervix, laminaria tents absorb surrounding moisture and gradually swell to a diameter of approximately one-half inch. While most of the swelling occurs in the first 4 to 6 hours, it may continue for up to 24 hours. Since this is a gradual process, the patient rarely notices pain. At the same time, the cervix is induced to ripening (becoming soft and flexible). The effect is often limited to local cervical ripening; however, stimulation of the cervix can induce labor.
The mechanism of action may be similar to that of a foreign body that, when inserted into the cervical canal, disturbs the normal chorioamniotic balance and initiates a cascade of prostaglandin synthesis. This in turn has myometrial-contracting and cervical-ripening effects. 10 The authors of one paper suggest the activity of laminaria may be because of its high levels of the prostaglandin precursor arachidonic acid 11 ; however, evidence of this purported activity could not be found in a recent review of the scientific literature. Cervical dilation may also be the result of partial placental detachment induced by laminaria. 12
Animal dataResearch reveals no animal data regarding the use of laminaria for cervical ripening.
Clinical dataLaminaria tents have been used to dilate narrow cervixes prior to dilation and curettage (D & C) and diagnostic procedures 13 ; to provide relief from cervical stenosis; to ripen the near-term or term cervix, especially in primigravidas; to facilitate labor 14 ; to induce labor at term with the adjunctive use of prostaglandins 15 ; and to induce first trimester abortions. 16 Laminaria tents have been inserted before the placement and removal of intrauterine devices and have been used to facilitate the placement of therapeutic radium within the uterus. 2
The effectiveness of laminaria in dilating the cervix and inducing labor has been evaluated in a number of clinical trials. In 1 study, the effectiveness of laminaria on the preinduction ripening of the cervix was compared with untreated control patients. Although laminaria was effective in reducing the duration of induction, there was no difference in the incidences of cesarean births. Endometritis occurred in 15 of 25 mothers treated with laminaria and 3 of 28 in the control group ( P < 0.05). Furthermore, 5 of 25 neonates from the laminaria group had bacterial sepsis compared with none of the controls ( P < 0.05). Three of the 5 septic neonates died. 10
In another study, 28 of 32 women were successfully induced with laminaria compared with 4 of 32 untreated controls ( P < 0.001). The mean induction-to-delivery time was shorter (12 1/ 3 hours vs 2 1/ 2 days) in the laminaria group. 14
A randomized study involving 175 women between 16 to 20 weeks of gestation compared the abortifacient efficacy of vaginal prostaglandin E 2 suppositories (PGE 2 ), PGE 2 + L. japonica , and PGE 2 + Laminaria japonica + concurrent treatment with intracervical PGE 2 gel. Abortion rates were higher in the Laminaria groups; however, no significant statistical difference was noted among the 3 groups. Reported side effects included pain and fever. No statistical significance was attained in accessing pain scores among the 3 groups. However, a statistically significant increase in febrile morbidity was noted with use of Laminaria ( P = 0.002). 17
Other usesSeaweeds of the species Laminaria have other pharmacologic properties. Laminarin, a complex polysaccharide, has antilipemic activity when partially sulfated and exerts anticoagulant activity similar to that of heparin when sulfated more extensively. The basal parts of the blades of L. japonica and L. angustata have been used as a hypotensive agent (ne-kombu) in Japanese folk medicine. Chemical analysis of the blades suggests that histamine and the amino acid laminine may be responsible for this hypotensive effect. 18 , 19 Alginate-containing algae and kelp have been shown to reduce the absorption of radioactive strontium in both animals and man and are used in the management of radioactive intoxications. 20
Dosage
Laminaria tents ( Lamicel ) have been used for cervical dilation, therefore no dosing information is required.
Pregnancy/Lactation
Laminaria may cause or contribute to maternal and neonatal infection. Avoid use.
Interactions
None well documented.
Adverse Reactions
A review of the findings from the early studies with laminaria suggests that it may be associated with a risk of neonatal and maternal infection. One manufacturer recommends swabbing the cervical canal with a suitable lubricant and antibacterial agent prior to inserting the tent, then packing the canal with antibacterial gel. The follow-up of 17 women who had laminaria tents inserted for the induction of abortion and who then decided to continue the pregnancy found no evidence of infection at term. 21 Other potential problems with the use of laminaria include difficulty removing the tent, breaking the tent during removal, 22 or rupturing the cervical wall and subsequent infection. Blood loss does not appear to increase following the use of laminaria tents in first trimester abortions. 23
Although laminaria tents possess many qualities of an ideal cervical dilator (eg, easy to insert/remove, slow expansion, painless dilation), persistent problems of infection and cervical injury have spurred the search for alternate types of dilators. Synthetic laminaria tents prepared from hydrophilic polymers provide increased levels of structure stability. 24 Synthetic tents have efficacy similar to that of prostaglandin E 2 tablets. 25
Toxicology
The spontaneous uterine contractions that may accompany the use of laminaria have been implicated in the induction of fetal hypoxia and subsequent intrauterine death. 15 Fetal activity should be monitored closely.
Bibliography
1. Morton JF. Major Medicinal Plants: Botany, Culture, and Uses . Springfield, IL: Thomas; 1977.2. Newton BW. Laminaria tent: relic of the past or modern medical device? Am J Obstet Gynecol . 1972;113:442-448.
3. Johansen HW, Akioka H. Salad from the sea. Sea Frontiers . 1988;34:136.
4. Windholz M, ed. The Merck Index , 10th ed. Rahway, NJ: Merck and Co., Inc.; 1983.
5. Zvyagintseva TN, Shevchenko NM, Chizhou AO, Krupnova TN, Sundukova EV, Isakov VV. Water-soluble polysaccharides of some far-eastern brown seaweeds. Distribution, structure, and their dependence on the development conditions. J Exp Marine Biol Ecol . 2003;294:1-13.
6. Tyler VE. The New Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies . Philadelphia, PA: G.F. Stickley Co. 1987.
7. The Drug & Natural Medicine Advisor: The Complete Guide to Alternative & Conventional Medications. Richmond, VA: Time-Life Books; 1997.
8. Lininger SW, Gaby AR, Austin S, Brown DJ, Wright JV, Duncan A, eds. The Natural Pharmacy . Rocklin, CA: Prima Publishing; 1999.
9. van Netten C, Cann SA, Morley DR, van Netten JP. Elemental and radioactive analysis of commercially available seaweed. Sci Total Environ . 2000;255:169-175.
10. Kazzi GM, Bottoms SF, Rosen MG. Efficacy and safety of Laminaria digitata for preinduction ripening of the cervix. Obstet Gynecol . 1982;60:440-443.
11. Crawford MA, Casperd NM, Sinclair AJ. The long chair metabolites of linoleic avid linoleic acids in liver and brain in herbivores and carnivores. Comp Biochem Physiol B . 1976;54:395-401.
12. Jonasson A, Larsson B, Lecander I, Astedt B. Placental and decidual u-PA, t-PA, PAI-1, and PAI-2 concentrations, as affected by cervical dilation with laminaria tents or Hegar dilators. Thromb Res . 1989;53:91-97.
13. Manabe Y. Laminaria tent for gradual and safe cervical dilatation. Obstet Gynecol . 1971;110:743-745.
14. Tohan N, Tejani NA, Varanasi M, Robins J. Ripening of the term cervix with laminaria. Obstet Gynecol . 1979;54:588-590.
15. Agress RL, Benedetti TJ. Intrauterine fetal death during cervical ripening with laminaria. Am J Obstet Gyneco . 1981;141:586-588.
16. Propping D, Stubblefield PG, Golub J, Zuckerman J. Uterine rupture following midtrimester abortion by laminaria, prostaglandin F2alpha and oxytocin: report of two cases. Am J Obstet Gynecol . 1977;128:689-690.
17. Atlas RO, Lemus J, Reed J, Atkins D, Alger LS. Second trimester abortion using prostaglandin E 2 suppositories with or without intracervical Laminaria japonica : a randomized study. Obstet Gynecol . 1998;92:398-402.
18. Funayama S, Hikino H. Hypotensive principle of Laminaria and allied seaweeds. Planta Med . 1981;41:29-33.
19. Chiu KW, Fung AY. The cardiovascular effects of green beans ( Phaseolus aureus ), common rue ( Ruta graveolens ), and kelp ( Laminaria japonica ) in rats. Gen Pharmacol . 1997;29:859-862.
20. Gong YF, Huang ZJ, Qiang MY, et al. Suppression of radioactive strontium absorption by sodium alginate in animals and human subjects. Biomed Environ Sci . 1991;4:273-282.
21. Schneider D, Golan A, Langer R, Caspi E, Bukovsky I. Outcome of continued pregnancies after first- and second-trimester cervical dilation by laminaria tents. Obstet Gynecol . 1991;78:1121-1123.
22. Borgotta L, Barad D. Prolonged retention of laminaria fragments: an unusual complication of laminaria usage. Obstet Gynecol . 1991;78:988.
23. Jonasson A, Larsson B, LeCauder I, Astedt B. The effect of cervical dilatation by laminaria tent in first trimester legal abortions on blood loss related to fibrolytic activity in the decidua and placenta. Int J Gynaecol Obstet . 1989;29:73-77.
24. Chvapil M, Droegemueller W, Myer T, Macsalka R, Stoy V, Suciu T. New synthetic laminaria. Obstet Gynecol . 1982;60:729-733.
25. Bagratee JS, Moodley J. Synthetic laminaria tent for cervical ripening. S Afr Med J . 1990;78:738-741.
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